I don't think it's the tickling thing. It's a fair hypothesis, but it doesn't feel right to me. To me I think it's the emotional connection of doing something with another person, and the physical connection of two (or more) people working together. Like, I'd say that throwing a ball up into the air and catching it again just isn't as fun as throwing a ball back and forth between people is, and there's no biological imperative there. There isn't a lust for tossing the ball with the boys. But it's a group activity, and group activities fill a different need than solo activities, which is a different biological imperative.
So I think joinking it fulfills only part of the craving, but leaves other parts unfulfilled, which is why as soon as that part recovers the body is like "okay, let's try again"





Right, but here's the trick: I can't do the same thing twice. So if I write it ugly the first time, that's the best that's ever going to be. What a waste of its potential! π