When one takes a shit and doesn't clean themselves, it dries, and another then has anal sex with the dry, dirty, poop butt.
"After drinking and chinese food last night, we got back to my place and (i didn't have and toilet paper) we started getting freaky, needless to say i got the crusty muffler."
by pennyrockit October 5, 2011
Get the Crusty Mufflermug.