The porn video tag "smooth-boy" refers to a young male performer who has an attractive, sleek, and well-groomed appearance. This could mean that they have a hairless or minimal body hair (chest, legs, etc.), as well as a well-maintained and groomed facial hair if they have any. In this context, "smooth" is not only about the physical appearance but also implies a sense of cleanliness and overall attractiveness that can be a factor in the viewer's preference or fantasy