C-SPAN isn't exactly the most entertaining channel on television. It provides a lot of political coverage that has been known to put people to sleep.
So, leave it to a bunch of pranksters to mix things up a little bit. There are a few people who seem to be legitimate callers, building up a story only to deliver a unexpected expletive. There are a few who blurt out something inappropriate right away. And there are a few who are able to get back live on the show a mere minutes after being kicked off.
Warning: NSFW Strong Language