used when length of time one will be away from an area is undefined, mainly a substitute for brb when it isn't appropriate.
Example Person #2 says: Maybe, oh wait mom's calling me, ibb
Example Person #1 says: K, IM me when you get back.
No, not the terminator way.
When you're online and you're going away from the computer and you:
A) Don't know how long you're going for
B) Be gone for a while
In short, a way of saying brb but if you're going for an undetermined/long time.
Ibb, gonna go take a nap
Ah, my mums calling me, ibb
your mum is gay.
Chatroomguy2:Why didn't you just say IBB?
Chatroomguy1:What does IBB mean?
Chatroomguy2:It means I'll be back, it's just easier to say IBB, so next time you have to leave but will be right back just say that, we will know what you're talking about.