Summer fashion: Board shorts in or out? plaid shorts in or out? basketball shorts in or out? Tshirts? Soccer jerseys?
I don't really know what's in and what's out, I prefer to make my own rules and wear what I feel like.
Every kind of shorts you mentioned is perfectly cool. T-shirts have been "in" for at least as long as I've been alive, and while I don't care for soccer jerseys or the sport that spawned them you certainly can't go wrong with one.