I've noticed that wearing boxers under basketball shorts is really popular now with guys here at the local college campuses. Just walking around a campus can reveal a lot about a guy's anatomy. I'm sure they realize there is a great deal of floppage with boxers, but there seems to be a new standard of acceptance among younger guys to reveal themselves this way...or there is interest in showing off.
I was out walking past an apartment complex with student housing, and there were three uber-built guys standing outside an apartment, all with no shirts and wearing basketball shorts, all flopping when they walked around. The shiney fabric of those shorts almost accentuates the affect. All three did it, it seemed to be the group uniform.
Not saying its a bad thing, I do it too. Just saying there is an increasing amount of floppage in and around campuses in this area recently. I've really been made aware that its more popular now than ever before with the recent warm weather and arrival of spring...