Dr Dance is familiar to reality TV addicts thanks to his frequent appearances on Big Brother's Bit On The Side.
The university lecturer, real name Peter Lovatt, analysed the behaviour of housemates on the axed Channel 5 show through their movement.
Now Peter has become a contestant himself, entering BGT in a mission to "get the whole nation to dance".
"When you move your body, some amazing things happen. Your mood lifts," he explained.
"So this evening, I want to show you a quick dance you can use whenever you're feeling a bit blue."
The 54-year-old invited the audience to stand, and soon the whole theatre was joining in with his dance tuition.
Everyone, that is, except a completely bemused Simon, who instead used his red buzzer.
This annoyed David Walliams, who began chasing Simon around the judges' desk, trying to get him to join in.
He retaliated by hitting David's own buzzer, much to the comedian's chagrin.
"I think it's a wonderful message that you've got, and it helps all of us. It makes us all feel happy," commented David.
"It's just a shame that there are pretty grumpy people who are not receptive to this whatsoever!"
Asked what he'd do next, Peter promised to go "even bigger", explaining: "We know so much about the psychology of dance…"
Simon wasn't interested, interrupting: "Without being rude, I've got the message."
Needless to say, the Syco boss gave Peter a firm no - but the other three judges' seal of approval sent him through to the next round.
Dr Dance isn't the only brush with Big Brother that Britain's Got Talent has had this year.
Ex-housemate Lotan Carter performed a strip show as part of magician Matt Stirling's try-out.
BB icons Nikki Grahame and Aisleyne Horgan-Wallace also cameoed in a musical number on spin-off Britain's Got More Talent.
BGT continues next Saturday at 8.00pm on ITV, when the panel will decide which acts will progress to the live shows.