"No shirt, no shoes, no service"

I think that if you cut your foot, or have some kind of rash or fungus, the rest of the people in the establishment probably don’t want your excrescences to be all over the place. They don’t care if you have fungi or bleed to death; they just don’t want to end up partaking of your glories.
Same as with a shirt; if you are wearing one, that is just that much less sweat that ends up on the back of a seat.

"No Shoes, No Shirt, And for gods sake No Excrescences, or No Service.