The FCC doesn't currently regulate cable. The airwaves are considered under its domain because they are :"free" and anyone with a TV can get them. So you can't do anything that would make a puriran blush on VHF or UHF.

Comedy central only has to answer to the subscribers. which is most cable companies around the US. So they can push the bounds of what is considered "dirty", particularly after hours, like with the secret stash stuff. But if they're too dirty, most cable companies will take them off of the basic cable package. The market regulates how dirty they'll be, and they walk that line quite well.

Certain people in congress don't like the fact that the government doesn't have controll of all media, and there has been a lot of talk in the last year of the FCC regulating both cable and satellite TV. The measure is dead for now, but not dead for good. And It's pretty much aimed at comedy central.