John Waters, the iconic director famously known as the Pope of Trash or the Prince of Puke, has never been one to shy away from a spectacle. When we meet in London’s West End, where he’s recovering from seeing both parts of the Harry Potter play (he’s not a fan himself, he says, but he went with a friend), he’s in a bright purple suit, that famous pencil-thin moustache still present, as it has been since he was a teenager. “I dressed just for you,” he purrs. He’s 70 now and has been in the business for six decades.

Among the many outrageous moments in his movies, his legacy will always be the infamous ending of his 1972 classic Pink Flamingos, which sees Divine – his friend and, until his death in 1988, his regular star – devouring a dog turd on camera. Waters remains as cheerfully provocative as ever but, in the aftermath of the US election, even he is wrestling with how to tell new jokes.

“I’m struggling to think of something funny to say, as all comedians are,” he admits. “I hate liberals who say: ‘I’m leaving the country.’ Oh, like it’s going to matter. You’re not that important, go ahead. But the only thing I can think that’s positive is that a new kind of anarchy is going to happen next.”

Waters has long been associated with a countercultural spirit. His early films in particular usually focused on gangs of outlaws marauding around his home town of Baltimore causing merry criminal chaos. But the re-release of one of his earliest feature films, 1970’s Multiple Maniacs, feels particularly prescient today, offering a snapshot of a time in which the US was in the midst of a wave of domestic terrorist attacks, student uprisings and protests. “You forget, there were skyjackings every day,” he recalls.

Multiple Maniacs was made on a $5,000 budget, a loan from Waters’s father, and it was the only one of his movies that his mother never saw. You can see why: its wild, sprawling plot, if you can call it that, involves the lawless adventures of an acting troupe of hippies and culminates in Divine being raped by a giant lobster. At 100% approval, it is Waters’s highest-rating film on Rotten Tomatoes. “When I look at it today, it’s like: ‘What were you thinking?’” he laughs. “I will be the first to say that it is ridiculous.”

‘I don’t want to be a faux-radical film-maker at 70. I did that’

Ridiculous it may be – by his own admission “the camerawork looks terrible”, and when people forgot their lines, he just kept rolling – but, for all of its chaos, it’s a surprisingly familiar and timely picture of growing activism, anti-establishment sentiment and youth rebellion. The film was shot towards the end of 1969, the most radical year in the 20th century, Waters reckons. “It was right before everything ended. Woodstock, Altamont, the Manson murders. It was a movie to comically go against the hippy values.”

Dreamland regulars Mink Stole (left) and Divine in Multiple Maniacs. Photograph: Janus Films

In Multiple Maniacs, the hippies are part of a travelling roadshow called Lady Divine’s Cavalcade of Perversion. Human exhibits include a gerontophile, a woman with hairy armpits, and “two actual queers, kissing each other”. Early in the story, the gang kidnap the Cavalcade’s “straight” audience, tie them up and forcibly inject them with drugs. Waters recalls one screening where this went down particularly well.

“The first time we had the premiere of the restored version was at the Provincetown film festival and this guy came over and said: ‘Acid must have been pretty good back then.’ And it was! People I know did shoot up acid. Even I never did that. Shooting up acid is really radical.” I didn’t know you could. “Oh yeah. You pull it right out of you at the height of the trip. Talk about a rush. My mother always said: ‘Don’t tell young people that stuff.’ And now I’m telling the Guardian!” He looks delighted.

Waters says he has watched Multiple Maniacs with young people after its recent restoration and it still resonates. “I’m not saying it hasn’t dated; it’s dated in way that it might be more appalling today than it was then. It was a punk rock movie. I look back on it now and think: ‘Oh my God, all this stuff about killing cops – not even the most radical group would say anything like that today.’ And you forget, in the 60s, ‘Off The Pig’ was a common slogan on a march, which is shocking today to look back on.”

Political activists use humour as terrorism to mortify your opponent. We need that again, and with Trump we’ll probably get it’

John Waters in London, January 2017. Photograph: Sarah Lee/The Guardian

However, he feels that the humour of radical groups from that era, such as the Weathermen, is the key to finding a new radicalism today. “These are political activists who use humour as terrorism to mortify your opponent. We need that again, and with Trump we’ll probably get it. He’d be an easy person to do it to because he has a short fuse.”

Waters says you could still have a Cavalcade of Perversion. What would be in it? “See transgenders in the bathroom! Or see the President of America! I hate reality television. I don’t think I’ve ever watched a reality show, ever, and now we have one.” He never watched The Apprentice? “Never. No! I hated him before. I hate a hopper. A hair-hopper is someone who pretends they’re rich, who really wasn’t brought up very wealthy but now tries to brag that they’re rich, and they spend too much time on their hair.”

The late Edith Massey maker her debut in Multiple Maniacs. Photograph: Lawrence Irvin/Janus Films

He doesn’t watch television himself (he reads instead, though says: “I know I’m missing something good”) and yet Waters has had a number of TV development deals in the works. Sadly for fans, none have yet come to fruition and he hasn’t made a feature film since 2004’s A Dirty Shame because it didn’t make enough money. “That’s fair, that’s what Hollywood’s about,” he shrugs.

Has he thought about crowdfunding? He looks mortified. “I own three homes. Am I gonna go out and say: ‘Send me $10?’” Well, rich people often do. “I’m against that. I have too much money to panhandle. They all want you to make a movie for under a million dollars, which I don’t want to. I don’t want to be a faux radical film-maker at 70. I did that. I don’t need to do it again. I can make a movie for $5m, which used to be a routinely low, independent movie, but there’s no such thing as that any more.” But, he says, “I’d make a movie again if they said yes.”

In 1988, Waters had a bona fide hit with Hairspray; it has since spawned so many offshoots that it’s practically an industry of its own. “They change it each time, and that’s why it works each time, hopefully,” he says. “As long as they don’t make a new version exactly like what came before, and don’t change it. That’s when it will stop.” There was the John Travolta-starring 2007 Hollywood remake; a hugely successful stage musical; and a recent live television adaptation in the US, on NBC. But a more surprising part of his legacy has come in the form of an inspirational quote, which has found its way on to posters, memes, T-shirts, mugs and even tapestries: “If you go home with somebody and they don’t have books, don’t fuck them.”

“It did catch on!” he laughs. He says he’s seen it everywhere. “At the Strand bookshop in New York, there’s an entire display of it! I don’t mind that they did it. Sort of I did. They censored it! They don’t say fuck!” The key letters are starred out. “That’s what infuriated me!” He mentions that a friend of his, the drag queen Lady Bunny, called him out on its veracity. “She said: ‘I thought he [Waters] liked criminals?’ I believe in my own words, but maybe I don’t always practise what I preach.” He laughs again, and offers up a sequel. “Basically, if they’re cute enough, who’s looking at the library?”

Multiple Maniacs is in UK cinemas from Friday 17 February and available to buy on Blu-ray from Monday 20 March