Sunglasses were cool, are cool, will be cool.
Sunglasses have been cool for a long time. In fact, they've been cool so long that some trend predictors say that the age of squinting is imminent, that you'll know the popular kids from the dweebs based on who's straining their naked eyes against the harsh sunlight.
But here's the thing: that's impossible. Because sunglasses help you see when it's bright out. So not only do they make you look cool; they make it so other people can actually see that you look cool. Whereas, you only squint when you can't see anything, so squinting can never actually replace sunglasses as the cool-guy-eye-thing because everybody would be squinting so hard that they wouldn't see all the cool people squinting.
This is all normal stuff that makes sense, which brings me to my next point: you should buy some of these Nautica Polarized Sunglasses.