A chinese finger trap is a tube comprised of interwoven strips of bamboo. It is a "gag gift" which you insert your fingers into. When the user tries to take his fingers out, the tube only tightens, trapping the fingers of the user. It is when you press both ends inward that the trap is unset.
Data was puzzled by a chinese finger trap during his briefing on the Tkon Empire, annoying Captain Picard. Geordi later showed Data the solution to the puzzle. (TOS: The Last Outpost)