The front desk clerk at the Beverly Hills Hotel is polite but puzzled. “Nora Lum? No, we have no one staying here of that name.” How about Awkwafina, I ask, spelling it out for him. He looks at me as though he thinks I might be messing with him. “Sorry, madam,” – is that a note of relief in his voice? – “no one of that name either.” I reach for my phone, but then I have an idea. Sandra Bullock? Suddenly I have the attention of all three front desk clerks. “This way, madam.”

“Who the fuck is Awkwafina? That’s everyone’s reaction,” laughs Nora Lum/Awkwafina (pronounced Aquafina) when I eventually find her. She and Bullock – or “Sandy” as Lum affectionately calls her – are both holding court at the hotel today to discuss their new movie Ocean’s 8, a female reboot of the Ocean’s Eleven crime comedy heist first made famous by Frank Sinatra and Dean Martin in 1960, then reprised by George Clooney, Brad Pitt and Matt Damon in Ocean’s Eleven, Twelve and Thirteen. In the movie poster Bullock and Lum are flanked by six other top-tier names: Cate Blanchett, Anne Hathaway, Helena Bonham Carter, Rihanna, Sarah Paulson and Mindy Kaling. “No one knows why I was cast,” says Lum, who has just turned 30. “Even I don’t know. Gary Ross [the director] really took a chance on me. He saw something in me that I don’t think I even saw in myself. Because of his confidence, I felt confident, too.”

Lum’s route to the top has been unconventional. In 2012, on her 24th birthday, she uploaded a rap video to YouTube entitled My Vag – sample lyric: “My vag speak five different languages / And told yo vag, ‘Bitch, make me a sandwich.’” Two things happened immediately, neither surprising. She was sacked from her job as a publicity assistant at a publishing company. And her father went ballistic. “He was screaming at me on the phone. He thought I was having a quarter-life crisis. And then we didn’t talk for a while…”

What no one expected, least of all Lum, was that the video would become a viral hit and launch her on a career as a rapper and comedian. “I still can’t believe it worked: that’s crazy to me.” Absurdly brilliant, the song almost defies description. Suffice to say that “vag” or “vagina” is repeated 53 times and the video features Lum – wearing a “horrifying pair of chemistry goggles” – delivering random paraphernalia from a (thankfully unseen) vagina: a violin, a cabbage, a live cat, a toaster.

Adopted by some as a sort of feminist anthem – a belated response to Mickey Avalon’s 2006 My Dick – the video has received more than 2.5m hits. Even Bullock is a fan. “At some point Sandy discovered My Vag and loved it,” says Lum. “She shares it, which is really cool…”

Views will no doubt increase dramatically this year as Lum hits the mainstream, appearing in both Ocean’s 8 and, later this summer, in Crazy Rich Asians. “It’s an amazing time to be in Hollywood,” enthuses Lum. “The landscape is changing. Here I am with an all-female cast and an all-Asian cast. I’m fairly new to this industry and I have not experienced some of the struggles I’ve heard about. Time’s up and it’s about time. No more bullshit characters for women, especially Asian American women. Don’t piss off whole communities of people.”

We meet first towards the end of her photoshoot. Although there are already at least 10 people in the room, Lum’s “wrangler” – as she calls her – is hesitant about letting me in, concerned I might write something revealing about the shoot. Fair enough: she’s just protecting her client. What she may not have grasped is that it is a little late to start protecting Lum. She has rapped about her vagina, joked about her apartment’s “semen-stained walls” and made quips about masturbation. Lum intervenes on my behalf. “Let her stay. What the fuck is she going to do? Write about my Spanx? Like I care…”

Lum is funny and relaxed throughout the rest of the shoot, putting everyone at ease. When the photographer asks her to lean back on a fluorescent bench, she cackles loudly and hams it up. “It looks like I’m giving birth on the subway.” The stylist puts her in a pair of incredibly high rose-gold heels and she totters around delightedly: “I’m terrible in heels. I look like a little baby trying them on.” Her voice is surprisingly deep – at odds with her slight frame. She changes back into streetwear for the interview – cropped black T-shirt, black high-top sneakers and khaki trousers. “I got them in Target [the American equivalent of Tesco] yesterday – I have no fashion sense. I then treated myself to Louis Vuitton sneakers. Target and Louis Vuitton. Who am I? What am I?”

Funny that she should beat me to that question. It turns out that even Awkwafina finds it hard to explain Awkwafina. “There is a duality between Awkwafina and Nora. Awkwafina is someone who never grew up, who never had to bear the brunt of all the insecurities and overthinking that come with adulthood. Awkwafina is the girl I was in high school – who did not give a shit. Nora is neurotic and an overthinker and could never perform in front of an audience of hecklers.”

So if the phone rang early in the morning and she answered half-asleep, who would she be, Awkwafina or Nora? “Nora. I’m Nora most of the time. But when I’m in a good mood I’m Awkwafina. When I’m in a bad, sad, lonely mood, it’s Nora all the way. When I come home at night from being Awkwafina, that’s Nora. I compare it to The Mask…” She means the Jim Carrey movie about a timid bank clerk who discovers a magical character-changing mask. “Thank God for the mask.”

Born Nora Lum in 1988, to a Chinese American father and South Korean immigrant mother, she grew up in Flushing, Queens. Her early years were marked by tragedy. Her mother was diagnosed with pulmonary hypertension shortly after Lum’s birth. “It was a very slow illness and she lived for four more years. I remember her, but I remember mostly when she passed… Obviously it was a very tragic situation, but I felt odd and uncomfortable when adults cried to me. One of the first emotions I ever felt was embarrassment. So I started trying to make them laugh.”

Her grandmother stepped in to help her father. “My grandmother was everything to me, she taught me that Asian women are strong, they’re not meek orchard-dwelling figures. She always knew I had something, not even star power but spunk – she got me singing lessons and we didn’t tell my dad, because he’d be like: ‘Why would you waste money on that, that’s just stupid.’”

At school, she was the comedian. “I was always the crazy one, the funny one. I’d do anything for a laugh, like dunking an ice cream in my eye. Everybody would be: ‘Oh my God, I can’t believe she did that!’ These were not intellectual jokes.” She attended a performing arts high school, where she played the trumpet. At 15, she came up with the stage name Awkwafina. “I just thought it was a funny name. And it was fitting that it had ‘awkward’ in it, because I am awkward.” After majoring in journalism and women’s studies, she went to China to study Mandarin, then worked at a video rental store, an air-conditioning company and finally a publishing company.

I don’t think I’ll ever carry myself like a star. Look at me now, bent over slurping up soup

Following My Vag, she released a rap album Yellow Ranger, then joined her idol Margaret Cho on Green Tea, a song which lampoons Asian stereotypes. Later she morphed into acting – appearing in comedy movies like Neighbors 2: Sorority Rising – and pioneered her own gloriously deranged web chat show Tawk, which she hosted from corner stores and laundromats, complete with an octogenarian, boombox-bopping sidekick – as well as a segment from her 84-year-old grandmother Grammafina, who delivers pearls of wisdom from a leather armchair in a darkened room, such as, “You want to throw a good party, you serve some hors d’oeuvres.”

“My grandmother’s such a ham,” Lum says. “She’s always like: ‘I’m so bad at acting.’ And then she murders it…”

In Ocean’s 8, Lum plays Constance, a pickpocket whose adroitness attracts felon Debbie Ocean, played by Bullock, who is planning a heist at New York City’s annual Met Ball. Before meeting the cast, Lum was terrified. “I had waking nightmares I would say something weird. But they welcomed me, they were so warm. There was so much laughter on set. I consider them my heroes – but now they are also my friends.” They keep in regular touch with a group text. “It’s always a joy to wake up to a text from one of them. We have a lot of gifs, a lot of laugh-out-loud jokes.”

Lum – who still raps and has just released a five-song EP In Fina We Trust – does not think she will ever feel like a movie star. “I’m physically insecure. It came with puberty, not feeling pretty. But when I say that to my grandmother, she’s like: ‘Bitch, you’re fine…’ But I don’t think I’ll ever carry myself like a star. Look at me now, bent over slurping up soup.” She says she finds it hard to relax into her success. “Even when I’m lying in bed at night I’m thinking, ‘What more can I do?’ I keep feeling I’ll pay for it all some way.”

Yet she thoroughly enjoyed one moment while filming Ocean’s 8 in New York. “We were shooting this glamorous scene and I looked up and saw the office I got fired from. I thought: ‘Oh my God, everything has come full circle.’ I left that job in pursuit of Awkwafina. And here I was shooting a scene with Rihanna. Getting fired from that job really hurt my feelings. Now I could just look up and say, ‘Fuck y’all.’”

Lum still talks to her grandmother almost every day. “She’s my therapist.” And even her father has come round. “Now he won’t leave me alone,” she says affectionately, “although I still, to this day, get random emails about government jobs from all the job lists he signed me up for. He just wanted good for me.” On a personal level, she says she feels very settled with her long-term boyfriend: “I’m extremely happy. I’m in love.” And yet: “I’m not sure I will ever be the kind of woman who can retire into a family.”

I ask her if Lum and Awkwafina will ever go their separate ways. “At some point they might have to. I don’t think an 85-year-old Awkwafina will be the most normal look… By then people will be laughing at me, not with me – I will be coughing loudly and yelling at birds. But then I look at my grandmother and she’s still pretty fricking cool.”

Our time is up. The hotel wants the room back and someone is ringing the phone and knocking on the door simultaneously. “They’re aggressive as fuck,” she grumbles, as she grabs her things. “Oooh,” she exclaims, spying a side table crammed with bottles of designer water. “I’m just going to steal these.” She grabs an armful, chuckling as we leave the room: “I guess I’ll always be a hustler.”

Ocean’s 8 is in cinemas from tomorrow