A sex act in which a person (male or futanari) rubs their penis in the cleavage between their partner's breasts. Also known as titty fucking or mammary intercourse. On Danbooru the Japanese term 'paizuri' (ぱいずり) is used.
If the penis is long enough, fellatio may also be involved at the same time.
The following tags are aliased to this tag: tit_fuck and titfuck (learn more).
The following tags implicate this tag: perpendicular_paizuri, multiple_paizuri, paizuri_over_clothes, and paizuri_under_clothes (learn more).