The best source of material for funny stories are going to be your own life again, I would caution you against trying to recycle something you saw on a late night talk show or a comedy special. If people want to watch Chris Rock or, or Jason Alexander or Jerry Seinfeld, they can watch them with a click of a button on their TV or their computer or YouTube. They don't need you to recount something. So your best stories with humor that will get last come from your own experiences. Sometimes it's just a matter of a little distance. Think about how embarrassing it was and sharing that with people and it will get laughs and help you make the point.