—pl.sons of guns.Slang. 1. rogue; rascal; scoundrel: That son of a gun still owes me $20. 2. a tiresome or disagreeable matter, chore, etc.
3. (used as an affectionate greeting, term of address, etc.): Charlie Humpelmeyer, you old son of a gun, how are you? 4. (used as an exclamation of irritation, surprise, dismay, etc.).