You're Fired. But the Irish comic can't bear to watch himself on screen.
"In my head, I'm a slim man with a full head of hair who moves like a cat and never mumbles. In reality, that's not the case," the 6ft 4in star explains, his sizeable frame perched rather incongruously on a chi-chi sofa in a trendy London hotel.
"Why would I destroy my feelings of self-worth by ever watching myself? I'd just sit going, 'How has this man managed to create a career in communications?"'
funnyman may lack feline grace and lustrous locks, but it's no wonder he has established himself as one the foremost comedians in the UK and his native Ireland.
Affable and quick, he's also a natural choice to front panel shows like Mock The Week, where he can deftly deliver fast-fire quips and rein in others when they veer too far off topic.
There is one subject he takes very seriously, however, and that's sums.
The maths and theoretical physics graduate is back with a third series of School Of Hard Sums, the Dave show in which he and Oxford professor Marcus du Sautoy attempt to solve a range of head-scratching conundrums.
Over the eight episodes,
O Briain will be joined by a range of comic stars, including Not Going Out's Lee Mack, Smack The Pony's Sally Phillips and Glasgow stand-up Kevin Bridges (who missed his GCSE maths exam to watch Celtic play Porto in the UEFA Cup final).
Challenges for the participants include constructing an eight-dimensional kebab and dividing up smelly cheeses in equal portions with the fewest possible number of cuts.
All great fun, surely? "The last thing we would ever want to do with the show is make maths fun. That's not the intention at all," O Briain insists.
"There's fun happening around the maths, but we're deadly serious about the maths. We don't care if you don't find it fun. It's for the people who find it fun anyway."
Maths and comedy are seen vying for space in O Briain's head in the show's animated opening credits, but the 42-year-old says he's better-rounded in reality.
"I wouldn't say my brain is constantly in turmoil about whether to be comedic or mathematical. There's so much more to my life.
"They're suits that you can put on depending on your mood or the situation."
Born in County Wicklow, O Briain now lives in London with his surgeon wife, Susan, and their children.
When he isn't filming or on tour, everyday life is "depressingly normal" in the O Briain household.
"I wake up with the kids, I look after them, they get sent off to some sort of holding pen for the day where hopefully they learn things," he deadpans. "And then I sleep more and then I await their return and I feed them."
Keeping his personal life private is clearly important to him .
"I don't really like talking too much about my kids," he explains. "They're not in the entertainment industry. I'm the one who's doing this job, so I'm not dragging them in."
Plus, O Briain says, "an invented version" of family life is much easier to joke about.
"I might come up with a really good joke about having four kids, and I don't need anyone going, 'No that's not the number of kids you have', and I'm going, 'But it's a great joke'."
Don't expect O Briain to crop up on a reality show any time soon, either.
"I've been offered Strictly Come Dancing three times. It will never happen.
"You get offered Strictly hopefully when you're still active as a performer. I have yet to be offered the jungle (I'm A Celebrity... Get Me Out Of Here!) or the house (Celebrity Big Brother). You either have to be way down, or at the back of a scandal before those two occur... But something to look forward to, eh?"
Dara O Briain: School Of Hard Sums returns to Dave on Tuesday at 10pm.