son of a gun

son of a gun  {n. phr.},  {slang}

1. A bad person; a person not liked.

I don't like Charley; keep that son of a gun out of here.

Syn.: BAD ACTOR.

2. A mischievous rascal; a lively guy. — Often used in a joking way.

The farmer said he would catch the son of a gun who let the cows out of the barn.

Hello Bill, you old son of a gun!

Compare: SO AND SO.

3. Something troublesome; a hard job.

The test today was a son of a gun.

Used as an exclamation, usually to show surprise or disappointment.

Son of a gun! I lost my car keys.

Compare: SON OF A BITCH.