TOO many of us are reluctant to grow up when it comes to our old friendships, according to DC Moore.

We are happy to carry on like we are still at university even as we enter our 30s – not wanting to admit, as the acclaimed playwright puts it, the ‘stakes are higher’.

That is initially the case for Lewis and Waldorf, who meet again a decade after graduating, in Moore’s new play Straight.

They immediately revert to their teenage selves, enjoying a raucous night out, until a drunken bet forces them to take their friendship to a whole new level.

Straight is based on the US film written and directed by Lynn Shelton – Humpday, which Moore fell in love with when he saw it two years ago.

The movie tells the story of two old pals who agree to shoot a gay porn movie together, which forces them to look at their friendship and their relationships with those around them.

"It’s a beautifully crafted film and the relationship between the two male characters is fascinating," says Moore. "I’ve got a lot of good male friends and it’s funny how those relationships change over time. The stakes definitely get higher the longer you’ve known one another, because things tend to matter more the closer you get to death, and friends can become a bit like a surrogate family.

"A lot of the time people try to pretend they’re still at university, getting drunk and being silly when they meet, not wanting to accept their friendship has changed.

"Perhaps more people are doing that at the moment because they can’t afford to buy their own house and they’re trapped in a sort of temporary lifestyle."

Humpday was a critical hit despite being part of the much-scorned ‘mumblecore’ movement, in which characters experience the same difficulties expressing themselves as us mere mortals.

Moore completely rewrote the dialogue for an English audience but stayed true to the spirit of mumblecore, which is part of what he loved about the film.

"I can see why some people find mumblecore annoying. It can seem like the writer’s too lazy to do his or her job, but when it’s done properly, like in Humpday, it works really well," he says. "That’s sort of how I write anyway, because people tend not to talk in fully formed sentences. Usually when you’re living in the moment, especially in very stressful situations, you don’t come up with the perfect retort. That only comes a couple of days later.”

Straight is directed by Richard Wilson, the man behind one of TV’s most memorable catchphrases.

Moore, who has worked closely with him since the beginning of the year on the script and more recently in rehearsals, insists Wilson could not be more different to Victor Meldrew.

"He’s a brilliant director and he doesn’t come with any prefixed ideas," says Moore. "He’s one of the least assuming people I know. He’s incredibly relaxed and I don’t think there’s any question of the cast being intimidated by working under such a famous actor."

Straight is at the Bush Theatre from Tuesday to December 22. Tickets, priced £10 to £19.50, are available at or from the box office on 020 8743 5050.