Pigeon stamp
A stain left on a glass surface after a particularly dirty bird, usually a pigeon, has flown into it. Tends to look like an angel or, in rare cases, the rabbit from Donnie Darko.
"THUMP"
"Dammit dude, a bird just flew into my window. I hope there's no pigeon stamp, third story windows are a pain in the ass to clean."
"Dammit dude, a bird just flew into my window. I hope there's no pigeon stamp, third story windows are a pain in the ass to clean."