This question appears very ambiguous and I am assuming that the 6-pack is warm, there is no ice available, and you don't have a cooler. If that scenario is accurate, the only idea I can come up with is to find a nearby stream that is flowing relatively fast and submerge your 6-pack for about 15 to 20 minutes. If there is no stream available I am afraid you will most likely be drinking warm beer... unless another well equipped picknicker with a cooler is either willing to trade you cold for warm or chill your beer while you wait!