Five by Five 

Before this phrase was used on Buffy, it was used on Jag, episode 10 from season 1. Austin spoke it to Rabb while she was in the hospital room.
This episode aired a whole year before Buffy season one hit tv.

"are you alright?"
"five by five"

Five by Five by Miss. Rogueh October 6, 2011

five by five 

Someone who's as tall as wide

She's definitely five by five, a real stout gal

five by five by Tim Jilbert April 16, 2003

five-by-five 

Originally an aeronautical term that is the equivalent to the modern "Loud & Clear". In slang usage, it means "great, fine"; popular in New England, it was made famous in "Buffy: the Vampire Slayer" from its overuse by the rogue slayer Faith.

"No worries, B. That vamp tried to kill us but I got mad skills. We're five-by-five here."

five-by-five by Sikozu Sta.-Ána September 3, 2003

one by five 

Lego nerd talk for "girlfriend"
-since lego does not make 1x5 pieces
-it's hard for nerds to get girls

I finally have got my one by five

one by five by Royce July 4, 2016

Five-By

When two people are approaching one another at an undefined rate, high five one another without stopping forward movement, and then continue to walk in opposite directions. A portmanteau of drive by and high five.

Yeah, I just gave Becky a five-by in the hall. It was awesome... High Five!

Five-By by Danz Ferdinand August 14, 2007

Five By 

Similar in method to a Drive By. A person in a car or similar vehicle, while driving past a pedestrian, reaches out the window and gestures for a High Five.
The Five By is completed if the other individual outstretches their hand to meet with the driver's.
This act can be made more impressive by Five Bying a row of pedestrians, two vehicles participating in the Five By with one another, or alternatively the driver and passenger(s) in the same vehicle all Five Bying simultaneously.
As the latter is significantly more difficult, bonus points should be awarded upon successful completion.

I just Five By'd this chick on my way here. I think I shattered some bones in my wrist but it was so worth it.

Five By by Sh!fT March 21, 2011