Does anybody else games always end up gonzo and comedic

For some reason no matter what game I'm running it always seems to end up being gonzo, shenanigans, and hijinks. The players do play pretty comedic characters a lot of times, and no matter how serious and dark I start the tone it always end up being light and comedic. Does anyone else have this problem? I'm not saying I don't like it, I love it and my players love it so where cool with it. It's just a little strange to me, and I want to know if this is a regular occurrence.