As long as I can remember, I was constantly pulling off practical jokes, some worked out just fine, some were a bit nasty. My brother in law asked if he could refinish his wooden racing sailboat mast in my work shop, since the mast was quite long. I swept up the end of my shop, set him up on some saw horses and he proceeded to sand, breach and refinish his beautiful, imported, 16 foot long competitive sailing mast. He cautioned me to keep the doors always locked, and not let my young kids get near it. All went fine until the last coat of varnish had been applied and was dry, and he was to come over and pick it up. In the mean while, I took my small son's mickey mouse handsaw that came in his little kid's carpentry tool box, and I cut a half circle with tin snips, on the tooth edge. I tenderly placed it upon the beautifully finished product, placed my son's tool box near by and scattered some sawdust on the floor below the fake saw-cut area and left the shop without locking the door! It appeared that the mast had been almost cut in two.
When the Sailor boy brother-in-law arrived, he tried the door, only to find it unlocked and admonished me because of it. As he entered, he snapped on the light, made the shocking discovery of his mast had been cut almost in half, and danced all around it shouting, "Oh No, I was afraid something like this would happen"! I rushed over and lifted the culprit saw from the mast, exposing the cutout portion but it didn't register right away. I had to restrain him from running in the house to tell his wife what had happened to his prized mast, (which of course wasn''t damaged at all).
It took him a while to settle down, and I don't think he ever forgave me for pulling off such a shocker. Everyone thought it was a riot, except him. Some years later, he died of a heart attack, but my sister-in-law assured me it wasn't because of my prank, he had not been taking his medication as he should have and the old ticker just gave out on him.
Hey, I got a million of 'em, anybody else got some gems you can share?

Roly ~~