When two men are engaged in a heated argument and it is clear no resolution will be made, one male will say "size up", prompting both participants to expose their penises. The one with the larger penis wins the argument by default simply because his penis is larger. No exceptions.
Male 1: "Dude, you're a fucking dumbass, McDonalds is definitely better than Wendy's."

Male 2: "Um, are you fucking kidding me, Wendy's is 10 times better."

Male 1: "Size up"

Male 2: Alright, fine, McDonald's is better.
by VillanovaJC March 14, 2011
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when a guy examines a girls thighs in order to see if she can take dick from him
have you seen her? i think i need to size up. not sure if she can take me. we are sizing up
by August 15, 2021
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when u measure each others cocks guys
''I'll measure urs if u measure mine'' That would be a size up.
by rw-lad August 13, 2008
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When a guy looks at you thighs to see if he would fit
When you size up you know the bigger the thigh gap, the looser it is
by Toryyuuuu July 17, 2021
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A way of saying a man got a boner, stiffy, erection, etc.

Sized up is a play on the phrase 'siezed up'.
Alexa: I came twice in a row thinking about last night

Jordan: Dayumm I just sized up hard
by Alexob April 6, 2014
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when you look at someone’s thighs to see how far your 🍆 will fit inside them.
“dude, i sized up my girl the other day. that sh¡t would fit all the way
by arf arf arf July 23, 2021
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To compare hand and finger sizes, leading to the comparing of other certain extremeties. This is a command given by one who is insecure about his manhood, and wants to reassure himself that he is as normal as anyone else.
Travis: "Size it up!"
Todd: "Stfu Travis."
by Lee Brody March 11, 2009
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