Listening now. Loved the "Who's On First" homage.
During the show, Wendy or Lindy ask the significance of John or Harvey in the bunny suits in whichever episode(s). (Sorry, only my first listen, while working on Other Stuff.)
Aside from any Easter references and general absurdity, I'd say there were two reasons for the bunny suits. Primarily, it's another reference to the movie, Harvey, since Harvey was an invisible pookah who took the form of a giant, bipedal rabbit. Secondly, could it be since the Easter Bunny (and Santa Claus) are imaginary / fictional characters? hmm, need to rewatch.... (I'm doing a slow rewatch, next up will be "Back and Back and Back to the Future.")