I would have to agree that if you have something of a "hobby relationship" built with one of the girls in particular, she would be more accommodating.
That would be kind of a very short version of it, at least, since most girls are different in how they view their business.
I know that unless it's summer, or when I'm not in school, I can't handle any sort of last minute requests. It's just impossible with the schedule I have. But for someone who I've seen a few times before and have had memorable experiences with, I'd be more likely to skip class to make it work out.