Comedians are extremely competitive. Each one wants to get the best reaction from the crowd. Many of them also know their place. If they're booked to go on after someone who they know will kill it, chances are they won't even want to walk up on stage. "How do you follow someone like that?" Imagine being the person who could potentially take all of the previous energy in the room and flush it down the toilet by choosing the wrong joke to start. Everyone will want to see the other comedian again. The worst part... the joke was still funny. It's the opening joke vs the previous comedians closing joke. This is actually harder to explain than I thought it would be. I'll stop rambling now. Look at all of these good comments. How am I supposed to top that. Get it? Imagine making the best comment was a life or death situation. Comedy is that serious.