I'm struggling with the horrible question.
So far I've only managed half-hearted jokes like "I'm campaigning to ban that question"
"Oh Fuck Off" seems a bit extreme.
I could go passive-aggressive: "Oh I always just relax and enjoy the lead-up to Christmas"
Perhaps not: "Have you lost your weight?" - that might be a mistake.
I'm thinking of a wry "well my bank balance has gone down so I must be doing something"
other answers please. And by the way I was first asked this question this year in mid-November by a hairdresser when attempting to relax at the salon.