A sexual
act or position in which 2 males simultaneously preform oral sex on each other. The term derives from the visual effect of the numeral: The top of the '6' and bottom of the '9' represent the penises while the bottom of the '6' and top of the '9' represent the mouths.
Very frequently, though incorrectly, conflated with
68 which is a similar act preformed my a
male/female pair (the '6' representing the
male and the '8' representing the female).