Last year at Anime Weekend Atlanta, somebody tried to sneak a bottle of whiskey into one of the panels. He got caught and claimed he "didn't know" alcohol isn't allowed in the convention center. Security chased after him, but I don't think they ever caught him. I also remember a dealing getting into an argument with security at (I think) Metrocon one year for trying to sneak a small bottle of liquor into the rave.
I don't remember anyone drunk at Mega, but that's probably because there's no hotel attached to the convention center. I've seen plenty of drinking other cons, especially in hotel rooms. I doubt booze is allowed in the convention center itself.
Franziska von Karma (Ace Attorney series- older and younger versions)
Lyn (Fire Emblem/Super Smash Bros. Brawl)
Raine Sage (Tales of Symphonia)
Grell Sutcliff (Kuroshitsuji, butler outfit)
Rose Bride Utena (Revolutionary Girl Utena, need new wig)
Twilight Sparkle's Gala Dress (My Little Pony: FiM)