A completely platonic, heterosexual event whereby two men defecate in the same toilet at the same time. As the bottom member of the stack, it is important to observe a proper tucking technique, lest an embarrassing and unsightly mess ensue. Once a double stack partnership is established, it shall persist for the duration of the bottom member of the stack's terrestrial life. Once the bottom stack member passes, the top member is free to pursue a new partnership, excepting that the new bottom member is related to the previous by marriage. A widowed bottom stack member forfeits their freedom to establish a new partnership.
Brian and Josh were a feared duo. They fit together like a jigsaw puzzle, their bodies working in perfect accord. Their office knew not to fuck with their double stack.
When two individuals need to defecate so bad, they use the toilet at the same time. One sits on and a little forward of the first person's lap, and they both relieve themselves.
Crikey, Bruce, I've got to shit so bad we're gonna have to double stack on a bun!
So there I was, minding my own business, when Jane busts into my stall screaming, sits down in my lap, and starts shitting right through my legs. I never thought I'd have a double stack on a bun!
This is a maneuver that requires both a male and female, excluding guy on guy since it will require an unobstructed anus. this however does not exclude girl on girl if a strap-on is readily available. This act starts off with the man(or the man in the relationship) sitting on the toilet facing the tank, and then the reciever mounting the the male. after starting intrecourse the female then procedes to shit which on most occasions will leave a trail of fecal matter on the scrotum.
"man i cant believe that girl did a michigan moose track double stack with me last night, and she wasn't even that drunk either!"