size up 

to estimate or assess someone or something

He did size up the potential destruction, but did not act decisively in the end.

size up by The Return of Light Joker May 25, 2009

Size up 

The phrase "size up", usually used in arguments, essentially means to "stand up and fight"

"Yo, no long talkin' b. Either size up or nize up"

In other words...

"Hey man, I don't want to do this long talking business anymore. Either stand up to me and let's fight, or shut up."

Size up by suwayy March 26, 2017

Size up 

To get a feel of someone's strength by observing them or a call out to get someone to fight you

This pretty simple term which was then redefined by tiktok idiots into: When a man looks if his dick will fit by checking out a girl's thighs.

Bro 1: Bro, I fucked your mom

Bro 2: Size up, bitch.

Bro 1: Bet

What tiktok idiots think it is:

Girl: OMG you're so gross, why are you sizing me up?

Boy: Umm... I wasn't. I don't want to fight

Size up by NNatty August 14, 2021

size up 

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.

size up by VillanovaJC March 30, 2011

size up 

when u measure each others cocks guys

''I'll measure urs if u measure mine'' That would be a size up.

size up by rw-lad October 8, 2008

Size up 

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

Size up by Toryyuuuu July 17, 2021

size me up 

when someone wants to fight you and to basically get on their level; usually said by someone bigger to someone smaller (in height)

boy: I know you aint messin' around with my girl
2nd boy: wanna fight me for it? let's go, size me up!

size me up by private.school.h0mboi February 23, 2011