Wanting a story

Wife likes biting his balls or likes to squeeze, slap, flick husband's balls....maybe experiments with a crusher, or some other toy(s)....she then decides that she can train/teach others on this kink. She then shows a friend or client how to ball bust using her husband as an example. The friend/client tests out new learned skills on the husband.
(He could be blind folder so he doesn't know who it is, or there could be a twist where the husband or friend/client have tension or awkwardness from not being blindfolded and seeing eachother in a new light)