Somebody (possibly an LWer?) proposed showing up to the car dealership without any cash or credit cards, just a check made out for the agreed-upon amount; the dealer now has no choice but to either take the money or forget about the whole deal.

While I don't remember this specific example anywhere on LessWrong, I actually did this last February. I vaguely recall some of the inspiration being discussions of strategy on LW, specifically the one about removing your car's steering wheel in order to win at the game of "Chicken".

(The rest of the inspiration was that I didn't trust the dealer not to screw with something once I got there, and a strong lack of desire to get into any sort of argument about it.)