A guy who makes passes at a girl who is already involved with another guy. Frequently using terms like "Weren't you in my Biology class?" - or "Weren't you in Mrs. Jones' Third Grade?". The name comes from the frequent donning of a Sheepskin jacket during the 'pass' phase. Many bold sheepskins will make passes at chicks who are with their boyfriends. Main habitat are local malls.
"Dude, look at that sheepskin trying to make a pass at your girlfriend."
What condoms used to be made of... used as a replacement for the word "condom" so people can't tell how perverted and disgusting you are.
Bob:Dude can I borrow a sheepskin?
Joe: Sure(hands Bob condom)