I've spent about 6 full years making a living by riding a bicycle, delivering everything from legal documents and blueprints to food, booze, and condoms. Generally this type of work takes place in the heart of the city, where there's a lot going on. Lots of things are all moving at once, and it's quite easy to hit them.

The first time I hit a taxi without falling on my ass/face/shoulder, but in fact kept going without any effect in direction, I was amazed. I had glanced off of the side of the car and then bounced again back into the lane when my tire hit the curb. Some lizard part of my brain took over, and I purposely hit the same car again, just to see. It worked.

Later I started using this as an offensive maneuver, first to cars that nearly killed me, and I started trying out low speed head-on crashes. Yep, I was able to ride directly into a building/pole/police truck and remain in the upright position. Once you learn it, and can use this in lieu of using your brakes, it's fun to note peoples reactions. Especially in the heart if the city, where theres a lot going on.