Sankaku Channel/predicament bondage

Predicament bondage is the art of restraining a person by bondage in such a way that there is a limited number of positions in which they can be, each of which are so uncomfortable that they are forced to shift their weight or position. Upon doing so, they place themselves in the other equally uncomfortable position.

Alternatively, one submissive partner may be forced to choose one position that causes pain to another submissive partner whom they know and love, with the only other position they're able to choose being a position that causes pain to him/herself, so that psychologically you have the conundrum of being able to spare your loved one the pain, but only by submitting to pain yourself, or else you must make the opposite choice of being "selfish". This type of bondage is used in BDSM and power exchange play.