One time, while commuting, I heard a couple cars in the distance approaching me from behind and it sounded like they were racing. There was fairly heavy traffic at the time and the first "racing" car changed from the outside lane to the middle lane fairly close behind me...the issue was the driver racing in the car following did not see me until his "buddy" changed lanes. I then heard a 4-wheel lockup skid behind me as the driver behind suddenly realized why his buddy had changed lanes. Needless to say, nothing will make you jump on the pedals harder that a car 4-wheel skidding up behind you.
Another time, I almost killed a stupid cyclist. It was night, I was sitting at a red light on the outside lane with a big 4-wheel drive pickup sitting next to me on the inside. The light changed to green and I barely started to accelerate, and the truck driver beside me honked his horn so I stopped; and a stupid cyclist flew by, through the red...in the crosswalk...no lights. Took me a few moments to recover...