Someone who seems friendly until you approach them and they look at you, laugh, and walk away!
Girl 1: Hey, you're in my physics class!
Girl 2: (Looks disgusted)
Girl 1: I sit right behind you I-
Girl 2: (Cuts girl 1 off mid-conversation by snobbishly laughing and walking away)
Girl 1: She's so Jonta I hope she trips and fall!