"Be right back." No longer taken literally, people just say it when they are going to be gone for any amount of time, whether it be 20 seconds or 20 minutes.
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*
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.
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...??