Is a hot dog a sandwich?
Merriam-Webster says yes. The National Hot Dog and Sausage Council says no. New York taxes it as one. Both sides, a ruling, and a sentence. Below: both sides as they'd actually put it, then the ruling The Judge gives when two people bring this one into a Settle It room.
Both sides
It's meat inside bread. That is the entire definition of a sandwich. Merriam-Webster literally lists it. Case closed.
Nobody has ever said 'I'll have a sandwich' and meant a hot dog. It has its own category, its own bun, its own council. It's a hot dog.
The Judge's ruling
Ruling: On the definition, Maya has it: Merriam-Webster added the hot dog to its sandwich list in 2016, and New York State's tax department treats it as a sandwich for sales-tax purposes. On the culture, Theo has it: the National Hot Dog and Sausage Council formally ruled in 2015 that a hot dog is its own category, and no human has ever ordered a sandwich and received a hot dog. This is a taxonomy question wearing a lunch costume. Legally and lexically, yes. In any conversation that matters, no.
Sentence: Maya may say 'technically' once, then never again. Theo buys the next round of hot dogs and does not call them sandwiches while paying.

Share the card, or better, send the loser the link. Sample ruling: in a real room The Judge asks each side follow-up questions first, then rules on what you actually said.
Sources
- Merriam-Webster, '10 Kinds of Sandwiches' (hot dog included)
- NHDSC, 'Is a hot dog a sandwich?' (2015 ruling: no)
- New York State Department of Taxation, sandwiches taxable (hot dogs listed)