Longman Dictionary of Contemporary English - son of a gun

~ n AmE old-fashioned spoken 1 a man that you are annoyed with  (That son of a gun didn't show up to fix the washer again today.) 2 humorous a man you like or admire  (John, you old son of a gun, where have you been?) 3 humorous an object that is difficult to deal with  (The sofa was huge, and we couldn't get the son of a gun to fit through the door!) 4 son of a gun! used to express surprise