The Vicar of Dibley star, a judge on the Andrew Lloyd Webber talent search, said that she hopes she doesn't slip up on the pre-watershed live shows.
"I'm a notoriously rampant swearer and enjoy expletives enormously," she said.
"I'm trying to use up all my foul language now so that I am severely depleted when it comes to the live telly."
The 54-year-old comedienne sits on the panel alongside rock opera composer Lloyd Webber and Jason Donovan.
Hosted by Amanda Holden, the auditions for Superstar launch this Saturday (July 7) at 7.25pm on ITV1.
Watch the trailer for Superstar below: