You can say that again 

It's a kind of term when you agree with someone, he/she. It shows that you are in one thought with that person.

Ex: (Mom yelling at us to be quick)

Sister: "Mom is soooooo IRRITATING!"

Me: "You can say that again" (showing that you agree with your sister (do you?))

You can say that again by seetheworld October 15, 2018

pleasure you can't measure 

Wow, isn't this the grate-ist catch-fraez EVAR!

Do not buy products with this slogan in thier advertising campaign. Ever.

pleasure you can't measure by Kung-Fu Jesus May 3, 2004

air you can wear 

A common phrase in the south eastern United States, particularly the Gulf Coast region. Description of an extremely humid day. Usually reserved for when the humidity level outdoors is above 90%.

If its so muggy outside the walls are sweating that's air you can wear.

air you can wear by Jlh1309 July 5, 2017

You can scan my ass! 

An increasingly common retort from customers checking out at Whole Foods Market as the cashier asks you if you have the Amazon Prime app to rescue some of your remaining paycheck.

I was with my friend Sean at Whole Payckeck when he rudely blurted out, “You can scan my ass!” which later seemed totally understandable when I saw the $150. receipt for his single bag of groceries.

You can scan my ass! by Dr Bunnygirl November 18, 2019

you can't be just a little bit pregnant 

It means that the situation that is being described is a binary. It is something that is either IS or ISN'T. Such as is the case when one is pregnant. One either "is" pregnant or "is not", there is no in between or partial pregnancy. It means it is a situation in which there is no ambiguity or no gray area. You can't be "just a little bit" of certain things.

You can't be just a little bit pregnant when you are talking bankruptcy. You can't be just a little bit bankrupt. You are either bankrupt or not bankrupt.

References:
Lou Mannheim (Hal Holbrook) in the movie "Wall Street" used this phrase while conversing with Bud Fox

you can't be just a little bit pregnant by idiomsfanatic April 13, 2007

Once you go blue, you can't undo. 

The phenomenon in which a normal conversation turns blue, becoming so riddled with sexual innuendo that it's rendered nearly impossible to steer back in a non-pervy direction. Every innocent comment starts to become a dirty double entendre, until eventually the entire conversation turns into a complete smut-fest from which there is no return.

Girl: Ah, who doesn't love stripper zombies in Portland? That'd go down like Jesus on a velociraptor.

Guy: I have to admit, when I first read 'go down'... I had rather blasphemous thoughts.

~ten minutes later, during which this term is invented~

Girl: Hmm, this Urban Dictionary thing is quite fun. Something for the annals of history.

Guy: Two n's - one 'n' is bad.

Girl: Yeah, I always thought that 'annals' was an odd word.
It really could so very easily be another.

Guy: Terribly easily. So, how is the entry? ...Oh, Jesus!!!!

Girl: Once you go blue, you can't undo.

Once you go blue, you can't undo. by The Terror Twins August 3, 2010

You can have her 

When a very hot chick is passed off by the dude next to you with bad taste.

Person 1: "WOW, that Victoria secrets model is fine"

Person 2: "Eh, you can have her"

You can have her by ShaanNEG February 14, 2012