I'm a charter member of that club, and have the scars to prove it. Did you know that you can jam TU gears with your finger tip? I do now.
However, the all time prize, although not tank related per se, goes to a retired Marine bull colonel. He bought an inboard/outboard boat from a friend of mine. Come late fall, and it's time to winterize the tub. He'll do it hisself because he did not want to get ripped of by the local marina. Gets out The Book. Said Book instructs to drain the built in fuel tank as Task #1.
Hmmmm. Not gonna get fuel in HIS mouth from the siphon hose. Goes and gets, and this is no BS, his wife's canister vacumn cleaner, inserts the hose therefrom in the fuel filler, and turns it on. The vacumn cleaner is now listed as Object #10466 in low orbit around the planet. The hair on his face and head was removed to just behind the ears, and the insuing conflagration took the boat, trailer, truck to pull same, and the garage with it. They did manage to save the house. Central VA circa 1980.
The lesson from this? Never give a Marine a vacumn cleaner.