We love to talk about stage presence and material as important aspects of a great comedian, but one aspect that is overlooked is the ability to read the crowd. Reading the crowd, is a comics ability to see how the audience is responding to certain material. When a comic reads the crowd correctly, they can taylor their material in such a way that they can get the best reaction possible.
One of the easiest methods of reading the crowd is by just listening to what the comics before you are doing. That is why most shows have a host or MC. While the host is up there warming up the crowd, the comedians on the show should be able to hear what topics are really working and what topics are dead on arrival. If you are listening, you should have no surprises when you get up. That is unless all of your material is about a subject that the crowd is hating with the MC (for the most part).
What if you are a host yourself? No one is going up before you, so how are you supposed to be able to read the crowd. That is when the demographics are the audience comes into play. Are they a younger crowd? Then they may not want to hear about how your hip hurts. Are they older? Then they may not react well to you saying that you are too old at 24. Now, this is not a concrete thing. You are basically guessing for a bit as to where you can take your audience.
For years, I have used jokes that I could throw up quickly to see if the audience will be into what I plan on doing. I also have two sets that I can use incase I guessed wrong. One show I was performing and I assumed by looking at them that I should do my family friendly material. They were not reacting to it. They wanted to go in the gutter, so I whipped out some of my more “blue” material and they were hooked in after that. The thing is, I don’t expect everyone to have that much material to pull from, so if you have material that can go a couple of ways this is a good time to pull it out. This way you have a safety valve in case you go up and they are not feeling it.
Reading the crowd to see where you can take them material wise is often overlooked, I think, because most comedians have a set list that they can not budge to far from, so if it isn’t working then they are stuck doing that material no matter what. That is why it is important to keep writing and performing. You can get really good at seeing what a crowd wants with experience. Have you ever seen a comic go up after someone crapped the bed and see them kill. They read the crowd and could see that the comedian before didn’t get the collective humor of the audience, and was able to kick ass. Start paying attention and you can do the same.