They may be expecting a hilarious speech because you may be quite funny in the pub – but comedy is a very different thing in front of an audience at such a high stakes event. Are you a professional stand up comedian? Have you spent your career honing your material and comedy timing in clubs and open mic nights? Probably not … if you're not a ballerina you wouldn't attempt a bit from Swan Lake, so why assume you can do what pro comics do? Avoid the temptation to tell jokes. And go easy on the unsavoury anecdotes.
Do not touch a drop of alcohol until you've finished. No, really. ' … I'll be more relaxed …' ' … I'm funnier after a few …' No. You're not. What it will relax are the tiny muscles that control your clear, controlled speech – and your ability to think.
And remember what it's all about, and keep it short and sweet. No-one ever complained that a speech was too short.