Image copyright Arista Records Image caption TLC were the first girl-group to get a Diamond record, representing sales of more than 10m

Twenty-five years ago, on 15 November 1994, TLC released CrazySexyCool - a pioneering blend of rap, soul and R&B that made them the best-selling female band in US history.

The title supposedly referred to the band's personalities: Lisa "Left Eye" Lopes brought the crazy, having recorded her vocals on day release from court-mandated rehab, after burning down her boyfriend's house in a jealous rage. Tionne "T-Boz" Watkins, with her no-damns-given demeanour and raspy vocals, was effortlessly cool; while Rozanda "Chilli" Thomas was, for the sake of this anecdote, "the sexy one" (she also had an incredible voice and no shortage of attitude).

Propelled by the hit singles Creep and Waterfalls, it became the first album by a girl group to reach diamond status (representing 10 million sales) in the US. Globally, only the Spice Girls' Spice has sold more.

To mark the record's anniversary, the band have announced a one-off show at London's Shepherd's Bush Empire next June; and Chilli jumped on the phone to the BBC to talk about the making of the album; and how they ended up filing for bankruptcy after its release.

They started with the title and worked from there

Image copyright Arista Records Image caption TLC in 1994 (L-R): Lisa "Left Eye" Lopes, Tionne "T-Boz" Watkins and Rozanda "Chilli" Thomas

Although the song Kick Your Game incorporates the phrase "crazy sexy cool" in its lyrics, the album's title predates the whole project.

"We went in letting producers know that this was the name - and that's how the album should sound," explains Chilli.

"CrazySexyCool was our version of I'm Every Woman. Every woman has a crazy or a sexy or a cool side. You can be all three, but one is definitely more prominent than the other."

What's the dominant characteristic for her?

"A-ha!" she exclaims with a hearty laugh. "It depends on the day. The crazy might be the more dominant one at times. But cool or sexy? I don't know. It just depends."

Waterfalls changed their career

TLC's signature song is a socially conscious ballad that tackles drug addiction and the HIV epidemic (making it the first number one single to mention the disease). It changed people's perception of the band, and earned them two Grammy nominations and MTV's Video of the Year award.

With its intricately-woven harmonies and rubber-band bassline, the track was evidence of the band's growing confidence in the studio.

"We were just beginning to understand how our vocals meshed together, with T-Boz's scratchy voice, my high notes and Lisa's rapping," she says.

"It didn't matter what type of song it was, once our voices got on there, it became a TLC record."

And what does "don't go chasing waterfalls" actually mean?

"Anything that's self-destructive, that's chasing a waterfall."

TLC knew the record would be a hit

Image copyright Getty Images Image caption The group won two Grammys - best R&B album and best R&B performance - in 1996

"Making the album was a lot of fun. We didn't feel the pressure of the second album jinx - we were just excited to be in the studio coming up with new material," says Chilli.

"And I remember when we were done, a guy at Arista records said, 'It's a great album and you guys will probably sell a couple of million'.

"We were like, 'A couple of million? We're going to sell five million. At least'.

"But we weren't looking at it like, 'We think we're great'. We just knew it was special. It was one of those albums where you didn't want to skip to the next song. It's rare to have a project like that."

The album received Prince's blessing

Image copyright Getty Images Image caption TLC had previously covered Prince's Get It Up for the soundtrack to House Party 3

The song If I Was Your Girlfriend is a cover of a Prince single - originally an ode to his girlfriend Susanna Melvoin, in which he fantasised about switching genders so he could have the same emotional intimacy she shared with her best friend.

TLC's version loses those psychosexual complexities, but otherwise sticks fairly closely to Prince's version. Chilli says they were careful to be respectful for one important reason: Prince wanted to hear the finished version before giving his approval.

"The fact that Prince even allowed it to happen was a big deal because he never approved anybody doing covers of his songs," she says.

"It was always, 'No, no, no,' and we felt like it'd probably still be a no for us. So when he gave us the green light we were like, 'Whaaaat?!!'

"After that, all we cared about was, 'Is he going to be OK with it?' And it's so crazy because, of course, we don't sound like Prince. Tionne's scratchy voice certainly doesn't sound like his.

"But he heard it and he loved it, so that's all that matters."

Their first magazine shoot got them in trouble

Image copyright Getty Images Image caption Lisa Lopes [L] was sentenced to five years' probation and therapy at a halfway house after setting fire to her boyfriend's mansion

To announce the album's arrival, TLC gave an interview to Vibe magazine - the first time they'd met the press since Lisa Lopes torched the house of her football-playing partner Andre Rison.

"I'm looking at wardrobe they'd provided and they had police uniforms and fireman uniforms," recalls Chilli.

"Everything Lisa had done was behind me. I wasn't even thinking about it. It didn't even dawn on me that they were being a little ratchet about having that type of attire for us to choose from.

"So I'm like, 'Oh my gosh, we've got to wear this fireman stuff! This is so dope!' And of course that was the cover - TLC: Burning Up The Charts and Burning Down The House!

"Lisa was on probation and of course the judge saw it, so it was like we were just some little bad girls being nonchalant about this huge situation.

"But I swear it didn't occur to us until the magazine hit the stands and I said, 'Oh my gosh, we're in so much trouble!'"

Then the band held their boss hostage...

Image copyright VH1 Image caption The scene was recreated for the 2013 TV movie CrazySexyCool: The TLC Story

Famously, TLC filed for bankruptcy shortly after CrazySexyCool was released. According to T-Boz, the record might have made $75m for their record company, but the bandmates were paid only $50,000 each.

Frustrated with being given conflicting information about who controlled their payments, the trio decided to go straight to the top - marching into their record label and holding Clive Davis, then President of Arista Records, hostage.

When the scene was recreated in a 2013 movie about their career, many fans thought it had either been exaggerated or invented.

"Oh no, honey, that was not fiction at all," laughs Chilli. "As a matter of fact, it was a little toned down for TV."

"We were hot [angry], because we didn't understand how we were selling all these records with nothing to show for it. So it was like, 'Alright, let's just go to the source'.

"We brought along some girls Lisa met when she was in the Diversion Center. These were big girls, huge and scary, and we put two outside Clive's office and one girl inside. And unless we gave them the nod, no-one could come in or out, no matter who it was.

"It was like a real movie and, looking back, I'm like, 'What were we thinking?' But we didn't have anything to lose."

Their financial troubles are over now

Image copyright Getty Images Image caption The band went on to sell millions of copies of their third album, Fanmail, with a more equitable record contract

After the New York Police Department intervened, the stand-off with Clive Davis ended; but the band won, and their contracts were re-negotiated (filing for bankruptcy was actually a key step towards restructuring their finances).

In recent years, they've also re-recorded all their old songs, giving them ownership of the masters, and a greater share of royalties.

"Now, if anyone wants to license any of those songs, they can come to us, instead of going somewhere else," says Chilli.

They're ready to celebrate CrazySexyCool's anniversary

How the album has reached its silver anniversary is a mystery, says Chilli.

"My great-grandmother used to tell me when I was little, 'When you become an adult, the years will go by super-fast'. I didn't know what she meant when I was a kid, but I get it now!"

But she and T-Boz are ready to take the record back out on the road in 2020.

"We have a bunch of beautiful visual surprises and we're very proud of the hard work we've put into putting the show together, so we're very anxious for you to see it," she says.

Is it hard to perform the songs without Left Eye, who died tragically young in a car accident 17 years ago.

"We felt [her absence] more obviously right after she passed, when we had to continue to work," says the singer. "But over the years you heal. And I don't think you can ever heal 100%, 'cos that's our sister and we love her. But her memory lives on through us, and we don't look at it as a sad thing any more."

And what does she make of the rumours that TLC will make their Glastonbury debut next summer?

"Is that what you heard? I heard that too. That's what I'm hearing," she giggles, slyly.

"I'm hoping. Fingers crossed, toes crossed, legs crossed. Everything that it's possible to cross, it's crossed."

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