A swinger who hides the fact that they like to have sex with multiple partners and denies doing so, while their partner on the other hand is completely open about his or her sexual encounters with other people.
p1: I THINK I COULD BE A CLOSET SWINGER!
p3: I shagged this married man last night.
p5: Please don't tell anyone. If my husband knew he'd kill me, even though he shagged his brother's wife last night and told me to leave the house for a few hours.