Short for brb, which some people use literally, and are gone anywhere from 3 seconds to 5 minutes. Some people, however, use it much more loosely, and will be gone for hours on end, and usually come back making a truly shitty excuse for why they were gone so long. Used mainly in IM conversations.
1. Proper usage
Person #1: LOL
Person #2: I'll brb, gotta take a shit
Person #1: kk
---1 minute later---
Person #2: k back
Person #1: coo

2. Improper usage
Person #2: LOL
Person #1: brb
Person #2: alright
---15 minutes later---
Person #2: ...hello...?
---45 minutes later---
Person #2: you there!?
---4 hours later---
Person #1: I'm BAAAAACK!
Person #2: What were you doing? Scratching your genitals?
Person #1: NO! Never, I would never ignore you! I was... uh... painting my toenails?
Person #2: psssh *signs off*
by MrCuddles November 19, 2006
When someone doesn't feel like talking to you...
Me: Hey, what's up!?
Person: Nothing.
Me: Oh that's a shame!
...
Me: So what's new?
Person: Nothing much.
Me: Cool!
Person: brb
Me: Okay! :)

*Person signs off, never to return*
by Dr. Onuki December 22, 2007
What you type into an IM window when you don't want to talk to that person anymore. After typing, you simply don't talk to them anymore. Thus you are spared from their company and they are not offended.
"omg dn't u just luv star wars episode 2?!!1!?"
"brb"
"ok lol!"
by Faggoty Ramone June 4, 2007
Stands for "be right back". Used in IMing. Some people actually do come right back after saying brb. Most people don't come back after saying brb. Brb is used for an excuse (some of the time) so that the other will stop talking to them, but they won't have to go offline. Usually responded to by "kk" which means "kay, kool"
Guy: HAHAHHAAHAHAHAHAAHHAAHHAHAHAHAHAHAHH THAT WAS SO HILARIOUS!!!!!
Girl: Um...that wasn't funny..at all.
Guy: HAHAHAHAHA...aha...aha.... SO yeah WHATS up? HAh, isn't that so FUNNY how IM captilizing SO randomly??
Girl: Sure...
Guy: IKR??
Girl (thinking that this guy has spazz issues): brb.
Guy: kk!!!
24 hours later...
Guy: you there...??
by ishouldbedoinghomeworkalready December 27, 2011
The ultimate 3 letter phrase to avoid unwanted online conversations
Annoying person: Grrr i hate everything!

You: hehe yh

You: brb

Annoying person: OK

{close window}
by pretty-pissed December 17, 2007
brb doesn't just mean "be right back". That is a lie. When a woman tells you brb over chat (JUST brb, nothing else) that means she doesn't want to talk to you anymore. If she says something like "brb for 5 minutes my mom is having a heart attack" then MAYBE, just MAYBE, you can try to believe she genuinely has to get off the chat. Watch out for this guys, if a girl texts you this, you're probably wasting your time. The best solution to brb is to LET IT GO.
Me: So, I really had fun last night, we should totally do it again, don't you think? How does tomorrow night sound to you? ;)
Girl: (Another day with this douche bag? fuck that!!) brb
Me: Um...okay. :) (Damnit, I fucked it up again! This is the third this month!)
by crv93 September 18, 2010
An expression used in AIM conversations. Though technically meaning "be right back", it is more commonly used as an excuse to leave a conversation with a person you don't want to talk to anymore.
catluver00003: so how many cats do you have??????
joexx: brb
by Arabella Quag May 19, 2008