If you want to be really nasty, I had a friend a few decades back who was thoroughly feed up with the volume of junk mail he kept getting.

He was a scuba diver, and he made his own lead weights for his weight belts by salvaging the little curved strips of lead they use for balancing tires and melting them in a mold. He had a lot of small lead "ingots" laying around, so he would take the "return postage guaranteed" envelope, stuff a lead weight into it, and mail it off.

Nasty, nasty, nasty (snicker snicker)!

Don Firth