After Metro Transit Police received flak for arresting a 12-year-old girl for eating french fries in the Tenleytown station, you’d think the Washington Area Metropolitan Transit Authority would have backed off its no-tolerance campaign against illicit munching. But some Metro employees remain vigilantwell, sort of. Last Friday, a man and woman hopped on the No. 92 bus at 18th Street and Columbia Road NW with Burger King bags in hand. After grabbing his seat, the man pulled out a french fry. “Eating on the bus will get you a $50 fine,” the bus driver announced quite loudly. “Oh!” the man responded, crumpling the bag. Another passenger, sipping from a plastic cup, protested. “Someone could drop a chicken bone on the floor, and you could slip and fall!” the driver responded adamantlybut without admonishing the beverage drinker.