Late to the danbooru party, but its more than simply avatars and keychains, it was a regular trend on 2chan's Touhou board for a while and seems to have come to be known as "GyateKora"/"ぎゃてコラ", at least on Pixiv.
Come on, what's the matter?Woof Woof!!Woof WoofNekomuraHello.Today's Kyouko-san 2Hello!!Meow Meo-...*tremble tremble tremble*Meow MeowNot gonna say it?*snicker snicker*