Put aside the "Baby, It's Cold Outside" fight, and make way for:
A hot dog is a taco.
A sandwich is stuff between two pieces of bread. A hot dog doesn't qualify because the ween is nestled in a bun-- which is one folded piece of "bread". So, they theorize that a hot dog is a taco.
The only way I think that hot dogs and tacos are related is that some "hot dogs" are in search of a (pink) taco.
However you feel, just shove them both in your mouth and enjoy.