I’m not sure having one really skinny arm would be that useful, but I suppose entire X-Men have been based around being able to manipulate the size of your body. So yeah, if I had any control over it, being able to change the thickness of my arm might be useful.
DAVID: Well, I guess it was inevitable you'd write one good strip.
JUSTIN: Why is my one arm thinner than the other?
DAVID: I got bored while drawing and started watching MacGyver.
JUSTIN: So you stopped paying attention to scale?
DAVID: Nah, I just thought if you were ever trapped in a room with a bomb you could use it to pick the lock.