Sports for nerds. As a bonus, it delivers a relatively even playing field between those who rely on physical gifts and those who want to analyze the motion of the ball.

Important note: make sure to buy the authentic Wiffle Ball™, replete with the long yellow bat. It's patented technology, man... and in this case it's actually better.

Of course, this requires going outside -- but takes a surprisingly small amount of room.

Also worth noting: true wiffle ballers make up absurd rules. Hit the octopus and you are OUT.