United Kingdom, Aug. 17 -- Kelly Clarkson has swearily revealed why she has banned her children from watching her notorious movie debut From Justin to Kelly.

The 44-year-old singer revisited the critically panned 2003 musical during the final night of her Studio Sessions Las Vegas residency at the Colosseum at Caesars Palace on Saturday (15.08.26), bluntly telling fans more than two decades after its release: "It's s***."

Kelly made From Justin to Kelly with fellow American Idol contestant Justin Guarini immediately after becoming the talent show's inaugural winner, but told the audience appearing in the film had been a contractual obligation.

After spotting a fan wearing an Etsy-made shirt inspired by the movie, Kelly joked: "Well, it...