Robin just slapped John again. "If you shut up I'll help you!" he said, though he would have anyway.
He flicked out his butterfly knife, and he twirled it around a few times, because he was goddamn Robin Hood and that was what he did. Then, quick as lightning, the blade shot out and he sliced through the bindings on one of John's arms. It would take him awhile to work through the other three limbs, but he would be able to get himself out. Then Robin flipped him off, and they took their leave.
Once they were all out of the building Robin just grumbled, "the Fox," and said nothing else.