100 Teeth and a Hulk

This is a riddle that was overheard by a teacher at Mrs. Ender’s school.  It’s a middle school, and this was an eighth grader.

What has 100 teeth and can hold back the Incredible Hulk?

My zipper.

Come on, admit it, you laughed.  And then groaned and maybe said "oh my god, eighth grade."

Ender is out.