The action of an extremely fat lady that is taking a shit, once done, she is so fat that she can not reach around to wipe her ass. Instead she reaches between her legs and wipes from crack to split. Much of the time this act ends with the women spreading the shit into her vagina causing an infection that smells like shit!
90% of all fat chicks give themselves the rusty split.
by Wun Hung Lo January 08, 2006