No Tab, No Pepsi Free...

tab and pepsi free aren't in the refrigerator at homer's. they weren't around in 1955 either when marty mcfly tried to order one in back to the future. the beverage he was given instead is something you can get every day at homer's... what was it? if you know the answer you'll get double punches toward a free drink today (or tomorrow)! special thanks to billy ford for researching today's trivia.