I picked up a copy of the student-published humor magazine from a local university today. It was... bleh.
That's the problem. Most people think they can write funny stuff. Few people can.
Back in my high school days, I was on the staff of our school paper. Every year, we published a spoof issue. We also got students who wanted to write for the spoof issue alone, and not for our regular issues.
Needless to say, we turned them away. After all, why add someone to the staff if he or she is only going to write for one issue out of the entire year? They've got to prove their chops, y'know.