ˌson of a ˈgun noun [singular] American English spoken

1. a man you like or admire – used humorously:
Duke, you old son of a gun, how are you?

2. a man that you are annoyed with:
Somebody go tell that son of a gun we’re all waiting here.

3. an object that is difficult to deal with – used humorously

4. son of a gun! used to express surprise

[TahlilGaran] Dictionary of Contemporary English ▲

son of a gun
1.
a man who is unpleasant or who has made you angry.
He's one mean son of gun - so be careful around him.

2.
if you call a man or a boy a son of a gun, it is a way of showing affection for them.
The little son of a gun has done it again - he's won all his races.

3.
a way of referring to an object which is causing problems for you or making you angry.
The computer's crashed and I don't know how to get the son of a gun working again.

[TahlilGaran] English Idioms Dictionary ▲

Son of a gun!
[American & Australian, informal]
something that you say in order to show that you are very surprised and shocked.
Son of a gun! I can't believe they put her in jail for that!

[TahlilGaran] English Idioms Dictionary ▲

son of a gun
• son of a gun/bitch
a horrible person, a difficult task
I wish that that son of a bitch would stop using my camera without asking me.

"This is a son of a gun. I can't fix it at all."

[TahlilGaran] English Idioms Dictionary ▲

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.
Synonym: 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.

[TahlilGaran] English Idioms Dictionary ▲