colas Modeled after the city’s popular gun buyback program, a group pushing for a tax on all beverages that taste good, is offering Brooklynites gift certificates redeemable at farmers’ markets in exchange for their soda and other sugary drinks. For those that actually venture out to East New York to take part in this stunt, the exchange rate isn’t all that bad: $2 for a can of soda, $6 for a 2-liter bottle. |NYDN|