insecure?

The outdoor University pool is open year-round. On warm sunny days, there is a migration of students to hang out by the pool. Many undergraduate girls (who look like they also have spent a fair amount of time at the tanning bed) lay out - but there will also be undergraduate boys and the occasional grad student.

On my walk to work, I pass several of the sorority and fraternity houses. Recently I have noticed lounge chairs on the flat roofs of some of the frat house - and in the afternoons, males doing their own sunbathing. Why do they lay out on the roof instead of by a cool, refreshing pool? Perhaps they have their own insecurities.