I often wonder about these kinds of fetishes. Why are bunny costumes considered Sexy by some people? I guess it comes down to porn or perhaps it all started with Jessica Rabbit.
Rabbits breed like crazy and multiply fast. Rabbits have been associated with fertility for centuries in pagan traditions. The rabbit is the symbol of the germanic pagan goddess of Spring and fertility, Eostre. I suspect there is a connection here.
Playboy bunnies were a thing, going all the way back to the 60s, so that rules out Jessica. I think it’s the mating habits of rabbits that got things started.