"No shirt, no shoes, no problem," reads one sign in this open-air fish shack. The lack of strict dress code might have to do with B.O. having started out as a wagon on Duval Street some 25 years ago. "Cold beer sold here," reads another, and it's true — the bottles are kept in ice-filled coolers. Right there you've got two-thirds of B.O.'s allure. The final and most definitive reason for heading here is the food: fresh, simple, delicious, and relatively cheap, as a fish wagon should be. The house signature is the cracked conch sandwich: thin strips fried and, like all sandwiches here, dressed in key lime dressing and slipped into soft Cuban bread with lettuce, tomato, and sliced onion ($12.50). Fried grouper, shrimp, and fish du jour sandwiches are equally satisfying ($9.50 to $12.50, a dollar extra if grilled). Dinners, served 4 to 9 p.m., showcase same seafood selections but with choice of two sides; select the fresh-cut fries, which just might be worth the drive alone. Although we recommend the fish here, many fans swear by BOMF's half-pound burger ($9) — BOMF standing for "Buddy Owen's Mother's Finest." Buddy is the owner. Next time you're in Key West, head to the corner of Caroline and William streets and say hello to him at his very excellent little restaurant.