When Mary-Kate and Ashley Olsen decided to launch StyleMint, a monthly t-shirt club a la Kate Bosworth’s JewelMint, the twins promised they’d jump back in front of the camera together for the first time in years. This month, that means playing in a kiddie pool to promote their August contest. The designers want you to show them how you keep cool in August, via pictures or video (in which you’re wearing a t-shirt, of course). The winner gets a year’s worth of StyleMint shirts—you can enter via their Facebook.