I've tried many of the same things mentioned above (axcept running over stuff intentionally). I also have 2 other "games" that I enjoy playing.

1. I try to slow down as slowly as possible, basically I try to see how long I can slow down the person on my a$$ before they figure out what I was doing and just pass me. I think the record thus far was getting a lady on her phone to go 50 in a 70 zone. It took a few miles but it was funny as hell.

2. This one is my favorite. If the timing is right, I'll try to bait a tailgater to follow me real close on an expressway offramp. I like the cloverleaf offramps. I can rail around the corner at 70 no problem, that big old Ford Excursion has no chance in hell. If you do it right you can even catch their facial expression when they figure out they are going WAYYYYYYYY too fast for that corner!