Years ago, I was working on some fluorescent lights in a kitchen - if I remember correctly, it was a bank of about 8 4-foot tubes (4 ballasts). I had removed the wires and later on wanted to check the circuit hot. I touched the wires together, forgetting about the load attached - got a spark that was enough for a couple of pieces of molten copper to drop to the floor, leaving some burn marks on brand new linoleum. Ended up deducting almost the cost of the job off my invoice.
Another time I had stepped in some roofing tar, and one of the very few times I decided not to remove my boots, managed to track it onto a customer's brand new off-white carpeting. Spent a few hours scrambling to remove the tar with a rag and paint thinner, strand by strand, before the customer came home from work. I must have done a good job though, as the customer never did complain about it - mind you the customer has never called me back again for more work either!
