A Dirty Sanchez occurs when the passive partner (male or female) is sodomized and a coating of mucus/feces/lube remains on the shaft of the active partner's penis. He pulls out and the passive partner fellates him, drawing the member into his/her mouth through tightly pursed lips. This acts to squeegee the matter from the penis into a thin line or bead encircling the mouth. It forms a John Waters's moustache-like deposit on the recipient's upper lip like the moustache on a Mexican guy (e.g., from a 1930s movie; hence "Sanchez"), or John Waters. (A "Filthy Waters" is equally descriptive, but that term hasn't caught on perhaps due to its being a bit esoteric.)
I butt-fucked my girlfriend last night and she got the cutest little Dirty Sanchez when she sucked me clean. Thus the Dirty Sanchez (etymological) is an artifact of another act—it just happens; no fingers needed.
by Sterling Pfeffernüsse January 10, 2011