a girl who is very good looking to the guy who is currently dating her - but quite ugly when seen by other guys. The guy dating this girl can see one way of the "optical illusion", but other guys see the opposite.

popularized by the collegehumor video of the same name.
A Conversation:

Jim: Dude, your girlfriend is so ugly!

Dave: What do you mean?

Jim: I mean she's not attractive at all.

Dave: F*%^ that man, I think she's gorgeous.

Jim: Whatever, she's an optical illusion.

6 MONTHS LATER - POST BREAKUP

Dave: I see what you mean, Jim. I can see the other side of it now. She was definitely an optical illusion girlfriend.

Jim: For real.
by epausti February 1, 2011
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