1
general::
A person who performs showy, often dangerous stunts, especially but not exclusively in sports; also, a showoff. For example, He was a shameless hot dog on the tennis court, smashing every ball, or She was a hot dog behind the wheel, screeching her wheels at every turn. The relation of this term to the edible hot dog is unknown. [Colloquial; c. 1900] 2. Also, hot diggety dog;hot diggety. An interjection expressing delight or enthusiasm, as in Hot dog! What a great gift, or Hot diggety! We got the best concert tickets after all. [Slang; c. 1900]
American Heritage Idioms