If you’ve ever had a hot dog outside the Metropolitan Museum of Art, you probably got it from Dan Rossi — aka the Hot Dog King — who sleeps in his van parked outside the landmark to protect his coveted spot. In the nearly 20 years that Rossi has been slinging dogs outside the Met, he’s become quite the Big Apple legend — something he says he, quite frankly, “doesn’t get.” “As far as ‘icon,’ I’m it, I guess. I enjoy it a little bit, I just don’t understand it,” the 74-year-old Marine veteran told The Post with a laugh...