What do sharks do for fun?

Sharks don't really display any "playing" behavior. That being said, some species will correlate in co-operative groups to work towards a common goal such as hunting or protecting. Also, in some species, females will group together to protect their unborn young. Scalloped hammerhead sharks also migrate in groups. For the most part, though, sharks are solitary predators and don't work well in groups and certainly don't "play."