noun
sex play; erotic play
Euphemistic or literary term for sexual activity, often implying playful or lighthearted eroticism. Not a clinical term.
彼らは桃色遊戯に耽っていた。
They were indulging in sex play.
Compound of 桃色 (pink, a color associated with sexuality) and 遊戯 (play, game). The exact origin is uncertain, but it likely arose as a euphemistic literary coinage.