Esse ponto de exclamação no fim me faz pensar numa expressão de aprovação que talvez tenha sido grafada incorretamente. Vejam aqui:
‘An expression of encouragement, support, or approval toward a boy, man, or male animal, used as a standalone interjection before or after a sentence. Largely presumed to be a corruption of the expression "that's the boy"; it is also sometimes spelled "atta boy." You won the spelling bee? Attaboy!’ (
https://idioms.thefreedictionary.com › ...
That a boy - Idioms by The Free Dictionary)