"We Wish You a Merry Christmas" is a popular secular sixteenth-century English carol from the West Country of England. The origin of this Christmas carol lies in the English tradition where wealthy people of the community gave Christmas treats to the carolers on Christmas Eve such as "figgy puddings" that were very much like modern day Christmas puddings. It is one of the few traditional holiday carols that makes mention of the New Year celebration. The simple chorus and holiday greetings have made it a popular finale to many holiday specials over the years.
Phineas and Ferb Christmas Vacation! - In this episode of Phineas and Ferb, Dr. Doofenshmirtz gets a visit from a group of carolers singing the song. When they get to the verses demanding he bring them some figgy pudding, Doofenshmirtz takes umbrage at this and fires up his Naughtyinator.
"A Cranky Christmas" - The song is sung briefly twice, though "happy" in the lyric "And a Happy New Year" is changed both times, first by Salty singing "And a Salty New Year", then by Cranky singing "And a Cranky New Year".
The song gets interrupted twice - when Gonzo sings "Now bring us some figgy pudding", Miss Piggy stops him, thinking he said "piggy pudding". He corrects her saying it's made of figs before adding "and bacon" under his breath. John Denver also has to calm down Animal when they get to "We won't go until we get some".
While most of the original lyrics exist, Orange interrupts the third verse (which is actually the second verse in this version) to ask what they are getting, and after Midget Apple sings the first two lines of the chorus, Orange sings "Even if you are stuck inside a pickle jar", annoying the others before they all sing the first verse normally and twice.