look up any word, like blumpkin:
 
1.
During anal intercourse, the male will remove his penis and reinsert it in the girl's vagina. The feces on his penis are transferred to the girls vagina creating a dirty muffin.
Last night, I was giving it to her in the ass, then before I blew my load I stuck it in her puss. By the time I was done she had one dirty muffin.
by Sammy Cayman July 08, 2005
 
2.
During intercourse, when a woman defecates on a man's scrotum after anal sex; Therefore turning his testicles into a feces flavored snack.
The old man's dirty muffin was devoured by the crack whore.
by Allen Schmidt August 02, 2004