While shooting at a 6-10-7 split with a pin in the gutter, the ball falls off the lane at just the right moment to hit the pin, which sends the ball bouncing accross the lane, and on the rails of the ball return, meaning, the ball came right back to me through the ball return. Freakin funny ask heck when it happened.
A friend of my was having a bad game, and got really pissed while throwing at a ten pin, however unknown to us, some debri from the machine fell into the gutter just ahead of where the 10 pin was. The ball hit the debri and went straight up into the machine (my friend is a power bowler), causing the machine to crash down onto the lane. It took a 2 inch gouge about an inch deep out of his detonator. I'm not sure the of the exact damage to the pinsetter, but I never seen anything quite like that.
Another person bowling at the same bowling alley a week early threw a similar type shot, except this went up prior to the pin setter, breaking the signage.
Needless to say, we don't bowl at that house anymore. Not because of what we did, but the damage to our equipment was unreal on a regular basis.