Bollocking Time (I don't know if I'm allowed to say that or if I should have put asterisks!)

The story:

I was listening to Christmassy songs with my family while we were putting the decorations up one year and said, "Those lyrics aren't what I think they are, are they?" My mum was in stitches when I said what I *thought* they were, but now admits that it really does sound like it and can't listen to the song without cracking up now.