Marc Jacobs enjoyed a relaxing holiday in St. Barts this weekend. He hit the beach on Christmas Eve and Christmas Day with two things in tow: fiancé Lorenzo Martone and an Hermès Birkin bag, putting the latter, multi-thousand-dollar accessory at severe risk of sandy infections. What do you tote to your ocean-side adventures? Suddenly our Jansport seems so … Jersey Shore. [Just Jared]