A dirty shane is when a man has a 9+ inch cock and knows how to use it. Bruise the cervix, numb the legs, roll the eyes, make her cum until that pussy dies!
"I hooked up with this guylast night and he was a total dirty shane, I couldn't walk after. My legs are still weak."
A dirty shane is a beer bong hose with a face mask on the end of it. It's used to blow a Shotgun (definition 4) such that the recipient must inhale through both nostrils and mouth which results in a stronger hit.
This delivers a stronger shotgun with less wasted smoke, and eliminates the issue of shotgunning another person's boyfriend or girlfriend, as the dirty shane act's as an intermediary.
when i dumped a dude named shane and then he goes off makin out w/some other girl, after he said he loved me and then calls me a bitch the next week-aka, dick head... ya, u kno what i mean. also, made a girl feel like a piece of shit.