Back up 

There are 2 common meanings:

1/Used in military or police force: Reinforcements, support, help.

2/Computer using: create your secured data in case the computer goes down suddenly, mainly to prevent data loss.

1/Police officer shouts via radio: "Shot fired, shot fired. Officer down. Unit 26 to base, we got a situation here. We need back up immediately!" - "Roger, just hold on. Back up are on the way."

2/Before installing Smart Windows Care, we strongly recommend you to back up you data first to prevent yourself from losing important data.

Back up by Mr. Bum Bum November 16, 2010

back up 

When you drive your car in reverse, you back up.

That moron scratched his car when he backed it up.
You should use both side and rear mirrors when you back up your car.

back up by BMatty November 29, 2010

Back up 

More comfortable way to say tampons or maxi pads in public.

"Hey, can you check aisle 2 for tampons back up for me?"

Back up by Elliegold April 16, 2014

back-up

A dancefloor technique to attract the attention of a partner. Essentially this involes backing your bootie towards your partner and getting close, often thrusting. This technique will initiate a grind type of dancing.

She's backing-up to you dog! Get in

Let's get on the dancefloor dog. We can back-up on those hotties over there

back-up by Dykester January 17, 2007

Back up that money truck! 

Back up that money truck! — Financial windfall that occurs because of a random accidental situation; or, because of purposeful criminal activity. The exclamation “Back up that money truck!” is yelled the moment one gets a gander of the settlement check; or, the first pile of money made from successful illegal activity.

1) My car got rear ended by a city bus going up hill on a sunny day at high noon! LAWSUIT!!!!!! Back up that money truck!

2) All of those knock off designer bags got sold and no one got caught. Everyone came back with pockets so swole with money; their asses looked like they had THE MUMPS!!!!! Re-up on the gear!!!! And then, Back up that money truck!

Back up that money truck! by Mind Hunter the Profiler June 15, 2023

back up plan 

Haplessly taken for granted just because it’s not “exciting enough” or it’s “too good”. A plan that will only be referred to when all else fails. When you become a back up plan you should
figure out a way to hit them hard with the realization that you won’t always be there for them to walk all over you when they have no one else to go to; that you’ve got your own plans too. Otherwise, you my friend, will forever remain stuck in that phase.
Checkout doormat

Person #1 : Hey bro so what’s our plans tonight?
Person #2 : Who said “we” had plans? Check back with me in an hour or two.
Person #1 : What, so now I’m a back up plan?

back up plan by lufituaed.bnim December 1, 2017

Back-Up Wife 

A girl who you will become your wife if the two of you are single at a pre-determined age.

Robin: Let's make a pact, if we both turn 40 and we're both single..
Ted: Robin Scherbatsky, will you be my Back-Up Wife?
Robin: A girl always dreams of hearing those words. Yes, yes, a million times, yes!

Back-Up Wife by drewdaspot June 6, 2012