Tons of things. They always make me and the other person laugh.
I was sitting at a table with some people. Now, I only knew about two of them well, and the others were strangers to me. About five of them. So, we were talking about the homeless situation where I live. (Not a problem at all, really.) And in the middle of conversation, as things got silent for just a split second, I shouted "Hahaha, they dont have any homes!" And then looked around with a stupid smile at all the other people at the table. As they were all chocked and completely taken by surprise, no one said anything. So for a while, it was just me looking around. Then I laughed awkwardly and looked down, coughed, hrm, hrm.... Dear lord that was funny. One of the two people I knew at the table started laughing his ass off. I joined in.
Did I mention I love The Office? (The original version, mind you.)
Another fun thing to do is to hug for a bit too long, or when youre shaking hands, sightly touch the other persons wrist with a finger, and draw tiny circles.