The iconic Flo's Hot Dogs is a tiny yellow shack on the east side of Rte 1 in York, not far inland from Nubble Light and York Beach. Hot dogs have been sold here since 1959 and it looks it. The inside has a lunch counter with maybe a dozen stools, but on a good day there might be 20 people standing in a queue behind the stools waiting for hot dogs.
There is a protocol to ordering dogs, and it is clearly posted above the counter. The whole thing is done in batches: First the hot dog lady asked each person in line "How many?". That number became our name for the next 10 minutes. After everyone in the current batch had given a count, then we went back to the start of the line and she asked "What kind?" The common choices are the House Special (Flo's Relish, mayo, and celery salt) and Loaded (the same plus mustard, green relish, and onions). You can get other styles, too, but those are the two that are most common. All come properly nestled in a fluffy white warmed Sunbeam New England-style hot dog bun.
Mayonnaise and celery salt? This may challenge your preconceptions about hot dog goodness. Run with it. You don't become a foodie pilgrim by being close-minded about food!