December 26 is the second day of Christmas and within the octave of Christmas (which extends to January 1). In a time when the laws of fast and abstinence were far more strict, St. Francis of Assisi was once asked if Catholics should abstain from meat when Christmas fell on a Friday. He said that on such a feast as Christmas that the very walls should be smeared with meat so that they too could join in the feast.
Cook your duck and goose and eat up. Penances can wait for after the Christmas season ends.