You’ve probably noticed it checking Instagram during the past few weeks, especially if you are a rock music fan: the coolest T-shirts of the season are dedicated to the groups that made its history, from Guns N’ Roses to Metallica. Where to find them? At the flea markets of course. They’re also online: we selected our current favorites to buy with just an click and to wear with a pair of jeans or shorts for a real groupie’s summer.