umbrellasite
An umbrellasite is someone who, unaware of the day's weather conditions, comes to school without an umbrella and begs others to come under their umbrella in between classes, somewhat irritatingly.
Guy 1: "Shit I forgot to bring an umbrella... Hey dude can I come under there?"
Guy 2: "No. Fuck off, you umbrellasite."
Guy 2: "No. Fuck off, you umbrellasite."