This is probably news to a lot of people: you should pronounce the “f’ in twelfth, as in the Twelfth Day of Christmas, ladidadi. Here’s your chance to sing it. If you’d rather listen to John Denver and The Muppets sing it, see the video below.
This gives me a golden opportunity to ask if you know how to spell the word, and if you hesitated, you might want to check out this very good list of commonly misspelled words.
They use the old-fashioned UK-US spelling divide, whereas GenevaLunch uses international English spelling guidelines, but they have plenty of company, mainly based in the UK or US, where they tend to forget that English is spoken and written in several other places such as Ireland, Canada, South Africa, India, New Zealand and so on.
And if you want to know more about those strange lyrics in the Christmas song, wikipedia offers some background.
Merry Christmas, with or without that cheap shopping list shortcut, Xmas!