Acronym for the popular phrase "What the balls". Used to show shock, disbeleif, confusion, and frustration over the Internet or text, in place of "WTF", "WTH", or "OMG".
*Facebook convo* Alex: "lol yeah I didn't expect that to happen."
Erin: "I know I was like WTB!"
or *commenting on your friends new profile picture* "wtb dude! How come I wasn't invited to this??"