I can't help but think that the kids call it an Easter song only by associating Bunny FuFu with the Easter Bunny. While I can see the relation between the bopping on the head and the actions of some goons with their infamous axe handles, I think it's a stretch. For a bunny to be scooping up field mice and bopping them on the head is delightfully incongruous, and I find kids are often entertained by that kind of absurdity. Not to mention getting to sing about and maybe act out some socially unacceptable behavior, along the lines of playing the "Whack-a-Mole" arcade game. There's my opinion, that will be 2 cents, please.
Of course now you've got me wondering, just where DID that song come from?