The presenter was mid-way through an interview with singer Tom Grennan when his co-host set about embarrassing him.
Tim, 49, and Simon, 54, were discussing karaoke when the latter revealed that his friend was partial to a bit of singing himself.
However, the interview started to go awry when Tom begged his interviewer for a quick little number.
Tim denied fans the chance to hear his dulcet tones, as he explained: “No, I don’t like people hearing me singing and I don’t like people hearing me speak French.”
Tom was clearly feeling cheeky, and set about asking for a lighter in his best French accent, while the Sunday Brunch host squirmed.
Simon joked: “Tim’s already feeling uncomfortable at the thought of someone speaking out loud in French.”
As he kept getting berated to face his fears, the host had had enough and laughed: “Right that’s it – the end of the interview.
“Tom, you’ve ruined it, you’ve broken the show,” he joked. “I’m feeling all uncomfortable now.”
As the show cut to a break, Simon couldn’t help but get one more cheeky joke in, telling Channel 4 viewers “au revoir”, leaving Tim squirming.
Sunday Brunch airs weekly on Channel 4 at 9.30am.