One who has/thinks they have a great deal of knowledge, but grossly overuses it.

Someone who, at a party, always finds people walking away from them muttering " What a loser. Doesn't he have anything better to do?" after quoting useless and/or inaccurate statistics to make him look more interesting.

A person that uses their knowledge/feigned knowledge to make someone feel inferior for no other reason than to feel intellectually superior.
Man at a party: "Discount our neighbors to the east and I think you'll find we've got a sleeping giant on our hands. A veritable sleeping giant."

Everyone else at the party: "What a loser. He is so mentally obese that there should be a Richard Simmons work out tape dedicated to him."
by Serendipidity August 11, 2011
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To eat as much shit as you like and never put on any weight.
"Dude, your like, Mentally Obese or something"

"Yeah, ya jealous?"

"Damn straight"
by HotBitch January 2, 2006
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1) A term given to people who are very smart, and hold much knowledge.

2) A term given to people who only have food on their mind 24/7
1)Oh man, Sarah got another A+ on her calculus test, she is so mentally obese

2)John: Dude I´m dying for a cheaseburger.
Adam: Stop thinking about food! Your so Mentally Obese!
by gordura pura November 25, 2009
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Eating lots and always wanting food but not looking physically fat.
"Wow hes eaten 6 donuts and still eating more, hes mentally obese man.
by J.56 September 12, 2009
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