Is it normal that i laugh at just about everything besides comedians?

I laugh at childish jokes and just someone's expression. But when a comedian makes a joke, I NEVER laugh. I find this really strange since they are taught to make people laugh. I usually don't even break a smile. But when a friend says something wrong I will start rolling around with laughter. I literally will laugh at almost anything you tell me, but a comedian.....I can hear the crickets chirping in the background. So is this normal?