This is a rebus that consists of the image of a pin followed by an O, a key, and another O
My informant encountered this rebus at a school fair. It stuck with her because it was the one word puzzle, the type she loves, that she wasn’t able to solve. She found the answer by asking the person at the stall, which was Pinocchio.
The rebus in itself is pretty simple, all you need to do is say each part out loud and meld the words together into one. The difficulty comes from how simple it is. Most rebuses make you think about the positioning of the symbols, and the O’s can be misread as zeros.