I have some friends like that, and let's just say that ahh..well I don't hang out with them a lot. Most of my friends are cool about hittin' people back and what not, so it's not too bad. Everyone usually has weed, we all just match and have a grande ole' time. I think I would just tell that friend that he's lucky to have gotten 5$ from you since your such a generous guy most of the time.