A GEI person is a Generally Excellent Individual. This is derived from the Japanese word gei, which means talent - most frequently heard in the phrase "tokubetsuna gei", which is a unique social party/parlor trick.
*Kyle makes a clever joke which utilizes a pun, but makes himself look like a fool*
Erik: Kyle, you are G.E.I. ya' gei bastard.
a pothead who is united......with other stoners??
Hey jesse are you a member of stoner united??
Jesse: Yeeaaahh, uhh, *whats your name*.......
A vagina. The word originated from confusion over what Seagate meant.
Awww yeah, I'm gonna back up 50 terabytes to that semen gate.