Also known as Dukey-Dribbling and Poo-Chugging is the act of pressing your and another person's anus together and defecating into the other person's anus, or the other person defecating into your anus.
Ray William Johnson: Last night I heard Sheila and MacDonald were Shit-Swapping!
Bart: What the hell is Shit-Swapping?
Ray William Johnson: MacDonald was letting Sheila take a fat dukey in his asshole!
The act of pressing your and another person's anus together and defecating into the other person's anus, or the other person defecating into your anus.
Ray William Johnson: Last night I heard Sheila and MacDonald were Shit-Swapping!
Bart: What the hell is Shit-Swapping?
Ray William Johnson: MacDonald was letting Sheila take a fat dukey in his asshole!