"Comedy's a bit like sex or drugs," reckons Stephen Grant.

"You get better at it over time but you do have fond memories of the first attempt."

Started in 1988 by the famous Edinburgh venue Gilded Balloon, comedy talent search So You Think You're Funny is open to new acts who have been performing for less than 18 months and who have yet to be paid for a comedy gig.

You may not yet have sampled the delights of last year's winner, the 22-year-old former National Youth Theatre actor Tom Allen.

But over the years this competition has launched the careers of everyone from Lee Mack and Rhona Cameron to Dylan Moran and Peter Kay (although Kay, who won in year two at what was only his second gig, disputes the term saying his career "was still at the blueprint for the ship stage rather than ready to have the champagne smashed off the bow".)

Tonight, under the watchful eye of compere Grant, some eight local hopefuls will compete in Brighton for a place in the Edinburgh final. And the organisers are predicting "an uncommonly high standard", since the Brighton heat has produced a finalist for the past three years.

But Grant knows that audiences are just as likely to be attracted by a sense of schadenfreude.

"There is that car-crash attraction of a normal person, with enormous hopes and dreams, being utterly crushed in a matter of minutes," he admits.

"I've seen people leave the stage in tears, run straight out of the building or sit with their head in their hands not moving for an hour. It destroys people. I used to play counsellor but I find it too depressing now."

In his years as a compere, Grant has borne witness to some truly horrendous acts, the worst of whom, he reckons, was a guy who stripped naked from the waist down and brandished a knife at the audience.

You may need to be a little unhinged to succeed as a comedian, he observes, but it's only a small journey to being mentally ill.

The most toe-curling moments, on the other hand, have been those in which wannabe comedians fail to grasp the fundamentals such as speaking into the microphone and standing under the lights.

"People go up on stage and think, 'Ooh, that light's a bit hot and bright, I'll go and stand in that nice dark area at the back'," he laughs, "and you'd also be astonished at how many people don't hold the mic properly.

"Some people hold it to their waist and can't understand why people can't hear them. But my personal favourite is when people can't get the mic back in the stand. They do their five minutes and then they're stuck there for another five trying to leave. Eventually, if you're lucky, they'll drop it and run.

Starts at 8.30pm. Tickets cost £7, call 01273 647100.