It is a mixture of two foods.

In layman's terms, a hamburger is a bun sandwiched with meat patties. A hot dog is sandwiched between hot sausages, sauerkraut, mustard oil, etc. The food in between is replaced by a beef patty in the middle of the hamburger. Hot sausage inside.

An American simple food, with hot sausage, sauerkraut, mustard oil, etc. in the middle of the bread. It is named after its shape like a dog sticking out its tongue and blowing out air.