It's obvious she wants you to show what a "hot date" you are after the movie.
> Your age, the current grade and your desperation level, those are the main point to think about. If you're underage then don't get busted. If your current grade is around C-B then don't do it, you can still improve your grades. If your desperation level is so high until the point you're willing to be raped by a 75 year old woman [trust me, no matter how much you think "oh, I'm gonna tap that", she will definitely be the one tapping you]
So yeah, that's about it.
I have good grades but if I were to be in that position then I will definitely reject her offer. You don't win, no matter how much you think you can win.