"Like the you stop when I say so or I'll break both your arms on the spot kind of thing," Shepard replies, drily, but since he's already agreed she catches the rope when it's thrown, and coils it around one hand with automatic fastitiousness, "And if you're really unlucky I'll tattle on you, to your boyfriend."

See? It's joke! Definitely a joke. Definitely she has not broken anyone's arms on purpose before. Certainly not. And definitely not both of them if that were the case, right? Right???

(Not right)

"Maybe you don't think so, but... Look, don't take this the wrong way; you need to work on you situational awareness."