What animal kills for fun?

Some of the other animals which have been observed engaging in surplus killing include orcas, zooplankton, humans, damselfly naiads, predaceous mites, martens, weasels, honey badgers, jaguar, leopards, lions, spiders, brown bears, american black bears, polar bears, coyotes, lynxes, minks, raccoons and dogs.

Do orcas like to play with humans?

The answer here might be friendship. There are many cases where nomadic killer whales have gravitated to humans, bonding with them and playing games. Trainers at places like Sea World say very little goes into orca training. The whales seem to understand people, and are eager to cooperate and create bonds.