Ok, so "bum" is a rather un-PC term.
Especially since I myself am currently quasi-homeless. Although, living out of a tiny RV where ever I'm parked today, without electricity, I somehow still manage to keep reasonably clean (I've got hobo-bath down to a science) and not drunk 24/7.
Unlike the guy who has spent the last several minutes trying to sit next to me and bum money off of me. And I think pick me up.
My initial response to him? "Sorry man. I'm homeless… Continue