I was once doing a minor repair to a sink.

I turned off the water under the sink and then used my pipe cutter to cut the supply line BELOW the valve I had just shut off. Alot of water can come out of an open 1/2" pipe!

I slipped walking in a truss attic and put my size 12 through the ceiling once.

Sawed through a beam once and knew I had cut a wire when my saw stopped working.

Drilled into a wall and melted the tip of my drillbit (lots of fireworks came out of the wall) when I drilled into a wire.

Roofing a house all alone one day and had my ladder blow over. I used to do some rock climbing so I figured I could use my safety rope and harness I was using (with some creative use of other stuff I had in my tool bag) and just rappell down. Got stuck on the roof edge, got my rope tangled up, ended up tied in a knot, dangling helplessly 6 feet off the ground. Cut the rope and landed on my (now completely numb) legs in a pile with my tools scattered all over the ground - unable to stand up. Just then the home owner pulled up.