Checking out crotches or cleavage is the start of non-verbal way of showing interest. Finding exhibitionists heightens the game. It is like "I double dare you".
I'm always looking there, although I've never looked up a guys shorts
None that I know of.
up shorts? umm forme no to much view of balls and im not a big fan of them lol but if you can see the shape of a guys manhood through his denim it certainly makes me smile