Big 69er 

Like saying 10-4 good buddy, only much more salacious.

Big 69er by dontcallmeshirlty May 21, 2003

Big Mac 69er 

When a girl shoves a Big Mac inside her and the guy eats it out of her ass.

Guy 1: I think your girls on her period.
Guy 2: Nah, that’s just ketchup from the Big Mac 69er she did last night.

Big Mac 69er by PussyfootedHoe69 December 7, 2019