dated A childish, petty response to an insult, essentially meaning "same to you." "Old man" refers to one's father. A: "You're a stupid monkey brain!" B: "Oh yeah? Well, so's your old man!"
So’s your old man!
exclam. The same to you!; Drop dead! (Indicates basic disagreement or hostility.) BILL: You’re acting like an idiot! TOM: So’s your old man! I don’t know what you said, but so’s your old man!