We only do two covers, but I enjoy 'em both!
First, there's "Don't Dictate" by punk legends Penetration - I play it with a mashed up section of Cameo's "Word Up" which works very well.
We also do Dead Kennedys' "Moon Over Marin". As we're a 2 bass band El Rapho plays a relatively straightforward version of the bass line, but I play it as if it was Magazine's "Song From Under The Floorboards", which also seems to work.