If you truly don't know, play your ignorance and explore what you don't know. Don't go for the joke. Let humor arise from the situation. As soon as you start to tell jokes, you treat you other players as objects. Comments to the audience are not to each other.
Wit is how one idea plays off others.
The rule of threes is inflexible. If something is done twice, it must be done a third time. There is no idea as good as the inevitable. So if in the middle of someone else's beat you have the feel of a great idea, let it sit a while. If later the idea is no longer valid, then chances are it was only a comment on the action.