The inability to concentrate on the simplest of tasks, because you're about to piss yourself.
Especially troublesome in career fields where intense concentration is required and you're stuck, literally, with "nowhere to go". Some such careers are pilot, surgeon, paramedic, and speed shooting competitor.
While driving to an emergency:
Paramedic 1: "Hey man, I gotta take a piss real quick before we get to this call." (Jumps in the back)
Paramedic 2 (Driver): "What the..."
Paramedic 1: "Yeah man, didn't want to show up to a CPR with bladder brain!"
Someone who only has the ability to remain information for about as long as they can retain their own water. They regularly ask you things that they've only asked you very recently.
Steve: "So what did Nick want you for?"
Johnny: "He wanted to know how to set up the printer"
Steve: "Again? Didn't you show him the last two days already?"
Johnny: "Yeah. The man has a serious bladder brain, he just can't hold on to information"