It's one thing to make some of your slightly buzzed friends laugh at a party, but it's a whole other ballgame to get on a stage in front of an audience and do stand-up comedy. To do any kind of live performance, you need to have a strong ego and nerves of steel. To do stand-up comedy, you need to be virtually insane. Almost everybody bombs their first time.
There's a common misconception that stand-up comics do nothing all day and tell little stories to drunken audiences at night. It's a lot tougher than that. Stand-up comics spend hours every day working on and perfecting their routines, and they have to be able to read their audience to know exactly what kind of humor they'll respond to. Before you go stand in front of the infamous brick wall, you will need some guidance.
Before even thinking of a joke, you need to build up your comic vocabulary.
To kill: To do really well. The audience loves you. To bomb: To do really badly. This is where there is a danger of tomato throwing. Dying: The process of bombing. Set: Your collection of jokes. ("I just memorized my set.") Setup: The explanation part of a joke. It's the part of the joke you're not supposed to laugh at--the exposition of a situation or story. Punch line: The funny part of a joke. What you're supposed to laugh at. Heckler: Someone in the audience who talks and interrupts a comedian in an insulting way, in attempt to make the comedian bomb. Blue: When a comic is "blue," it means he is using dirty language or talking about sexual or adult matters in an explicit way.
For more comedy terms, check out "Greg Dean's College of Comedy Knowledge's Glossary of Comedy Terms" (see Resources).