Exhibitionism and voyeurism

Exhibitionism used in its psychiatric sense means that a person likes others to see his (rarely her) sexual parts or likes other people to see him/her doing sexual things.

Voyeurism means that a person likes looking at the sexual parts of other people or likes to watch other people doing sexual things.

Christianity
5:28 But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart. and some Christians interpret that as meaning that a man can’t even look at his own wife that way. A Christian man can’t ever look at pussy, he can’t even look at his own wife’s (...) Can a Christian woman look at her husband’s *****? The Bible is less clear there so different fundy Christians probably disagree. Fundy Christians hardly ever give women more freedom than men so a good Christian wife should probably look modestly away when her husband comes to her undressed.

(Perhaps Jesus was not so keen on sex, perhaps Jesus was more touchie feelie with Mary Magdalene.) Due to this over the centuries goodly Christians felt their duty was to avoid looking at their wives or husbands  that way and even sometimes today that happens. So good married Christians used darkened bedrooms other places were just a little improper, they avoided mirrors, never undressed together and did everything between the sheets in the missionary position spoiling half the fun.

Consensual
Consensual exhibitionism and consensual voyeurism are not a problem except for sexually repressed Conservatives. In gay bath houses leaving a door ajar but not fully open can be a signal that others are welcome to watch but not to join in.

Non consensual
Non consensual acts of those kinds can be distressing for other people who don’t want to see something sexual or don’t want to be watched when they are doing something private and such Non consensual acts are commonly illegal in many democratic countries.