Phillip Schofield reveals the behind-the-scenes arrangements on This Morning and questions how he'll manage to broadcast for 24 hours non-stop on the Text Santa fundraiser.
Over his years on the This Morning couch, Phillip Schofield and his co-presenters have developed a handy 'get out of jail free' card when one of them is feeling ropey.
"If someone's been out the night before, you just walk in and say to the other one, 'You drive today'," reveals the 52-year-old, laughing. "There have been times when Holly [Willoughby] has come in and said, 'You drive today', and there have been times when I've said it to her."
As well as Willoughby, who is currently on maternity leave after giving birth to her third child, Schofield used the shorthand with Fern Britton, who he worked with on the popular ITV daytime show for six years.
He hasn't yet tried it out on Amanda Holden, who is covering for Willoughby, but is expecting the conversation to pop up soon, when he takes to the airwaves for a solid 24 hours in aid of the Text Santa charity appeal, on Monday.
Since starting in 2011, the ITV charity bonanza has drawn on its roster of famous faces to go the extra mile to raise money for a raft of deserving causes.
And this year, Schofield, who previously donned one of Willoughby's glamorous frocks in a bid to encourage viewers to donate, is spending an entire day broadcasting to the nation on ITV3, as well as ITV1 and 2.
To help him stay awake, he'll be joined by a string of famous guests (I'm A Celebrity hosts Ant and Dec will chat with him live from the jungle), and is becoming an honorary Loose Woman for the day.
With surprises he can't yet reveal in store, including his "biggest challenge so far", and the small matter of a day's worth of presenting to contemplate, Schofield's cogs are whirring when we meet to chat about his feat.
"In the world of charities, we're very, very new," he says of the event, which has so far raised £15m for good causes and will divvy up proceeds between Teenage Cancer Trust, Guide Dogs, WellChild, Marie Curie Cancer Care, Alzheimer's Society and Together For Short Lives.
"I just want everybody to know Text Santa exists. It's that whole raft of different charities that appeals to us as presenters. It's a big, important night for us, so if I can be responsible for my bit, getting the name out there, then that will be cool."
Though fully aware that his task isn't the "physically gruelling challenge that Davina (McCall) or David Walliams have undertaken", he still has some concerns.
It could go "hideously wrong", admits Schofield, who was raised in Cornwall and now lives in Oxfordshire with his wife Stephanie, and he's unsure what will happen during commercial breaks and whether he'll be streamed on another channel.
He also confesses that he's "crap" with names, and is worried that "a guest will sit down beside me and I'll think, 'Oh God - I can't remember what you're called!'"
One thing father-of-two Schofield, who started his career at the BBC as a radio bookings clerk before becoming a children's TV presenter, isn't concerned about, are calls of nature.
"With This Morning, you have to have a bladder of iron anyway," he says, chuckling. "If you can't go, you can't go and that's that. There's either time or there isn't, and if you do get to go, you've got to go really quickly."
Still, the prospect of presenting solidly for 24 hours is not one he is taking lightly.
A keen wine buff, he admits that any all-nighters he's done in recent years have "normally involved tequila and Holly Willoughby".
While he'll have to forego the booze on air ("That would be a recipe for disaster!"), Willoughby has "promised" he can chat to her if she's up feeding baby Chester in the early hours.
The two friends are still in touch, and Schofield recently nipped over to see the "gorgeous" new addition who was born this September.
"I took Holly and her husband Dan a big bottle of Champagne," he says. "She's had one for each of their children's births. For Chester, I went a bit bigger on the promise this would be the last one!"
Although he is missing Willoughby, Schofield loves working with Holden. "Amanda's perfect for the show. She's utterly filthy - she's got the filthiest laugh of anyone I know - she's like a drain!" he says. "She's such fun."
And he'll be relying on Holden's sense of fun to help him through This Morning on Tuesday, by which time he'll have been awake for more than 24 hours. "This Morning will get the rough edge of my temper. I may be a little curt. But we all know each other very well, so they'll forgive me a grumpy mood."
Once his presenting marathon is over, he knows he's on the home straight for Christmas, with his working year wrapping up with the big Text Santa televised fundraiser on Friday, December 19.
Whatever lies ahead for his 24 hours live on air, Schofield is up for the challenge.
"There are things I've said I will do for Text Santa," he says, hinting at the "personal challenges" which will remain a surprise.