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2.
1) A Boner
2) A children's Book from the '60's from which the term got it's name.
*Note that the term can be used two ways, to refer to a boner, or to address one.
1) I was sitting in math and got a major flat stanley.
2) Hi flat stanley, do you wanna come out and play?
by CJ McMastaKewlio February 10, 2009
 
1.
When an obese woman lies on top of a skinny man during sex. This results in a flattening of the man, slowly crushing his bones and compressing his organs. The man is then sent around the country in an envelope. Old people and retards take pictures with him at national landmarks.
When Sue and Fred have sex they do the Flat Stanley. Fred usually ends up in the hospital to have his lungs refilled. He's been told he only has a month to live.
by ghett0d3ana May 06, 2010
 
3.
The act of pressing down hard enough to feel the contour of the male genitalia through his pants.
I needed to check out his package, so I gave him a "flat stanley".
by Deedre March 17, 2005
 
4.
blowing your load while you're soft
d'jessica couldn't even get me hard, but i still blew my load flat stanley style
by shwoogie May 15, 2010
 
5.
One who lacks size in the boob/butt region, and therefore appears paper-thin from a side view.
(Girl walks past)
Guy 1- Dude she's hot I would bang her.
Guy 2- No way dude did u see her ass??
Guy 1- No I didn't.
Guy 2- Exactly cuz she's a flat stanley.

(Girl slips through crack in locked door, leaving the rest of the party to wait outside)
Student: Damn she's such a flat stanley.
by Two Jews in the Back January 27, 2011
 
6.
a fighting move that slams a guy down.
i gave him a flat stanley.
by daman October 28, 2003
 
7.
To screw someone so hard they become flat. An extremely rare occurence, but can happen.
Fredrick: How did last night go?
Bill: Dude, I flat stanleyed het so bad.
Fredrick: Nicely done.
by schmookerdingle August 29, 2014