I was about to go down on this girl but I realized she had mad mud crotch, so I said, "hell nah, put your pants back on and get the hell out, bitch... unforgivable!".
when someone hasn't showered for a couple days, has done some serious sweating, basically been able to wash their crotch for an extended period of time
"Man, Jill was all about messing around last night but I had just got bad from the gym and had nasty mudcrotch"-Chris
"How was the camping trip?"-Chris
"Meh fine but after not showering for three days Stacy had some mad mudcrotch, and she kept wanting me to go down on her"-Rory