Mary-Kate Olsen's Thong Slip

(From left to right) Mary-Kate Olsen treated herself to a beauty day at Aurelia and Adrian in West Hollywood on Saturday.

Mary-Kate let her thong slip as she picked up some food at the popular Joans on Third restaurant in West Hollywood on Friday.

Ashley Olsen went on a shopping trip at the trendy Maxfields store along Melrose Avenue in West Hollywood also on Friday.

20+ pictures of the Olsen Twins‘ out and about…