South Park creators Trey Parker and Matt Stone have taken to the West End stage to introduce their satirical musical The Book of Mormon.
Hundreds of fans had queued outside London's Prince of Wales theatre on Monday to see the first UK performance.
The Book of Mormon, which lampoons religion and musicals, has already been a huge Broadway hit.
To deafening cheers, Parker said: "It's very cool to be here for the fan performance."
He added: "We heard that a lot of you lined up overnight for tickets... and we want to say from the bottom of our hearts, you're... crazy. We don't know that any show can live up to that."
The Book of Mormon follows the story of two missionaries who are sent from Salt Lake City to preach in a remote Ugandan village.
Written by Stone, Parker and Avenue Q's co-creator Robert Lopez, the show is directed by Parker and Casey Nicholaw.
The Broadway show won nine Tony awards last year. It recouped its $11.4m (£7.3m) investment in nine months, making its money back in part by charging up to $477 (£304) for tickets.
The West End show is sold out until the end of July, with a small number of daily tickets available via a lottery system.
The show's content is not for the faint-hearted, with strong language and jokes about religion, Aids and female circumcision.
"We never sit down and say how can we shock," Parker told the BBC Radio 4's Today programme. "It is unconventional material for a musical. That's the sort of stuff that we love."
Stone added: "It's about two white Mormon boys who grew up in Utah and are sent to a place with Old Testament problems - and nothing they've been taught helps them at all with these problems."
Elder Clifford Herbertson, a senior spokesman for the Church of Jesus Christ of Latter-day Saints (the official name of the Mormon Church), said he thought the musical would raise awareness of the church in the UK.
"I think the important point is that it's entertainment, it's not education, so it will raise awareness but I don't think it will necessarily help people's understanding or appreciation of the church," he told the BBC.
Scott Brown, New York Magazine's theatre critic, described The Book of Mormon as a "wacky, irreverent tale".
"It's one of those revitalising successes," he told BBC 5 live Breakfast. "Broadway is like the pharmaceutical business - they crank out all these drugs, but there is just one that carries the rest of the market for a huge amount of time, and this was Broadway's Viagra for a while."
Londoner Christina Tencheva was among those who queued for hours on Monday for a reduced-price ticket to the first performance.
"It was outrageous in the best way possible," she said after the show. "I knew it was going to be rude in places but I came in with an open mind. I think anyone can enjoy it as long as you leave any prejudice at the door."
Anna Koscheck, a regular West End theatre-goer, noted the show's youthful audience. "I pointed out to my friend when we went in that everyone is so young. I don't think I've ever seen that before."
Matt Stone and Trey Parker met at the University of Colorado and as students created the indie film Cannibal! The Musical. Their cartoon series South Park made its TV debut in 1997.
The big screen version South Park: Bigger, Longer & Uncut earned Parker an Oscar nomination for best song in 2000. In 2004, the pair returned to cinemas with Team America: World Police, an adult satire with a cast of marionettes.
Stone and Parker then spent seven years working on The Book of Mormon, which opened on Broadway in March 2011.