In victorian times a man would get pleasure from sticking his john thomas up a duck, turkey or goose's rear end, whilst his dearest held it between her legs, and when the old chap was ready to shot his treacle the lady would cut the birds throat
hello! I came up with this saying! It isnt fuck a duck anyway, its fuck a ducky and it means OH FUCK IM IN TROUBLE! or OH FUCK, WHAT DID I DO NOW!? or even, OH FUCK, I FORGOT!