I'll be back,
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 #1 says: Hey you goin' to the movies with us tonight?
Example Person #2 says: Maybe, oh wait mom's calling me, ibb
Example Person #1 says: K, IM me when you get back.
Chatroomguy1:Hey I gotta go but I'll be back.
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 backjust say that, we will know what you're talking about.
Chatroomguy1:Ok, IBB.