OK, in my book a cub is a young guy, say 18-29, who just happens to be hairy. Not a chub, but not scrawny either. And not necessarily really really hairy either.
But it doesn't seem like that's a very popular category. It seems like most guys either prefer twinks, or else guys over 40, or chubs, or guys who are super hairy.
It seems to me when I was in high school and college, there were always a couple of guys in the gym showers who just looked really good, with handsome young faces and those great young bodies, but with hair on their chests.
I'd share some pictures, but for some reason it looks like you can't in this forum.