In reference to a Hammond B3, when you haven't played one before and you sit down to play but you can't because you wet your pants. In many cases you have to do many takes while recording because of nervousness and having to change your pants often.
Isaac: "I had to do way more takes then 6!"
Bob: "Why, did you B3 yourself?"
Isaac: "I had never played one before!"
Bob: "I almost B3'd myself the other day when that girl walked into the cafeteria!"
Isaac: "You and me both"