It is meat in bread. It is a sandwich. I'm not a massive hotdog fan unless it is proper sausage.

Also, what's the big deal with mustard. All Americans seem to love it but I don't know many Brits who like it. Ours must be different.

EDIT: We're having a barbeque tonight. I might try a dog with ketchup and mustard and I'll post the results here. Unless I throw up... then I'll just post it on Facebook like everyone else.