slang Someone or something that is exceptional or remarkable. The origin of the word is unknown. Boy, was that a humdinger of a game—I can't believe the winning goal was scored in the last two seconds!
humdinger
and hummer (ˈhəm(ˈdɪŋɚ))
n. someone or something excellent. (see also hum job.) Now, this one is a real humdinger. Man, that’s a hummer!