For once, Kerry Katona had the right idea

We were to form a choir. In came Lembit Opik, and David Van Day, complete with 'selfie stick'

It's been a weird 15 years in showbusiness … Friday, however, was probably the weirdest day so far. I got a call from ITV – they were doing their charity thing called Text Santa. They wondered whether I might be up for doing something on the night with Ant and Dec? The one thing I know about showbusiness is that Ant and Dec are good news. It was something to do with I'm a Celebrity... Get Me Out Of Here! – which I was on in 2012 – I didn't read any more. I said yes. I've got to stop doing that.

It didn't start well. I checked into the swish Mondrian Hotel next to ITV. Well, I tried to check in; they only had a booking for "Kerry Katona". The one thing I know about showbusiness is that Kerry Katona is bad news. The hotel made some phone calls and then gave me her room. "She's not coming, ITV said you can have it …" I didn't sleep well. Disturbing dreams that involved Kerry Katona eating a pillow kept me tossing and turning. Come the morning there was, thankfully, no sign of Katona. I got to ITV for the 9am start. The one thing I know about showbusiness is that "they" will always get you somewhere as early as possible and that you should always ignore call times. The problem is that I am obsessively punctual. I arrived to find that the recording was to be at around 3pm. "Never mind," said a friendly but stern woman who turned out to be the X Factor voice coach. "When more people arrive, we can do some vocal warm-ups and training."

My heart sank – singing, warm-ups, training … this sounded too much like hard work. Slowly, the "others" turned up. We were to form a choir of I'm a Celeb contestants and, as they trooped in, I started to wonder if someone had spiked my coffee and I was in a hallucinogenic pantomime. In came Lembit Opik, Gillian McKeith (panto baddie), Timmy Mallett, David Van Day, complete with "selfie stick" (the sort of thing people used to use to look up girls' skirts on buses), Fatima Whitbread, Jordan (who came as Katie Price) and various members of the last series.

For the next two hours, the stern woman made us do pointless vocal warm-ups and sing an appalling, tailored version of "12 Days of Christmas" over and over again until I started to understand the basic techniques used in Guantanamo Bay.

Eventually, we donned our "jungle" outfits and were herded towards the studio to meet Ant or Dec and the mystery guests – McBusted, two plastic rock bands fused into one. Timmy Mallett suddenly donned some wacky glasses and a foam mallet, like a teatime Thor. Jordan/Katie Price was asking me whether she should do Big Brother if the money was right. I felt very lost.

And then we were on and Ant and Dec grinned in shiny black suits and the audience were going mental while wearing tiny Christmas hats. Snakes were brought out, Gillian McKeith looked faint again. I relaxed. Someone had spiked my drink, this was all a bad trip … wasn't it?