Cousin willy

Nickname gave to Kaiser Wilhelm II of Germany in the BBC's rap "The cause of World War One! Origins: Rap Battle | WW1 Uncut - BBC" by king Georges V of Great Britain, today it's sometime used as a reference/joke in history meme circles, along with the German war dance of the same song, by the way the account of the same name is the 3rd most liked comment of this video.

Kaiser Wilhelm II: Still proud of my german war dance 108 years later
Georges V: Chill out cousin Willy, stop acting so silly, you be trippin' by flippin' the bird willy-nilly

Cousin Willie

A name for a pervert or pedophile, usually an old man.

"Oh my god Cousin Willie is staring at me guys"
Pervert: pedo perv paedo