My favorite convention moment so far was my interaction with a Domino's pizza guy. Usually I'll get reactions like "oh, what's going on" or "why are you dressed all crazy?" but this guy really made my day.
It had been a rough day. I had some issues regarding scheduling, had some fussy friends, ran the Homestuck draw party, had my horns break and was under a tremendous amount of stress (also my make up was wearing off big time by now)!
I ran up to the lobby to ask the hotel to take my bass out of storage, and as I was going to the lobby a pizza man stopped me. I turned expecting the "what's going on here?" questions but instead I got...
"Woah man. Your costume is really cool. Like I've seen a lot of cool costumes here but yours is really cool."
My Vriska cosplay was my first time doing make-up and sewing quite a bit so I wasn't all that confident but having a total stranger come up to me and saying that they really liked my costume after a long day was so amazing.
The only bad part was I didn't get any free pizza out of it! Darn!