Whether or not you know how to golf, those of the preppy persuasion will love girlsgreen’s cute, stylish polos and tees, terrific for the green or for everyday (see our review). For today’s birthday contest, one lucky winner (worldwide entrants welcome!) will receive a $75 gift certificate to the girlsgreen online shop. To enter to win, email us (by midnight EST tonight, July 11) the answer to the following question: Who are the two sisters behind girlsgreen?