I was riding about 20 feet behind another cyclist on a 3-lane (middle turn lane) road on my commute home a few weeks back when a car passed both of us really close. Did it on purpose too, as there was no other traffic around, and the turn lane was totally clear.

I just threw out my usual "middle finger salute", shrugged it off as another idiot and kept pedaling (I was wearing mitten gloves so I don't think my salute had much impact on the driver, but it made me feel better), but the guy in front of me totally blew up. He started spewing profanities and sped up to try and catch up with the guy at the next light. He was roasted and I think it could have been an ugly scene if he could have caught up with the guy.