Thanks, I'm glad you thought it was origional. I never really saw Sirius as malicious or a rotten human being, just a thoughtless one who didn't really consider how his actions affect others. I figured this prank had to be particularly thoughtless, because it had such a potential for hurting Remus.

I was originally intending to write further on, and in my outline, the next seen went like this:
Sirius: "James, please bail mine and everyone else's arses out of the shit I got them into"
James: *Facepalm*