"Son of a gun" is a popular expression used in a variety of contexts, ranging from mild surprise to anger or frustration. It can be used to describe someone who is clever or resourceful, but it can also be used to describe someone who is stubborn or difficult to deal with. Synonyms for "son of a gun" include "rascal", "scoundrel", "mischievous", "sly", "trickster", and "maverick". Each of these terms conveys a sense of playfulness or cunning, and they can be used to describe a wide range of personalities and behaviors. Whether you're looking for a subtle compliment or a blunt insult, there's a synonym for "son of a gun" that will fit the bill.