Gary and Susan appeared on the programme so that Gary could try and win her back after a volatile split.
He even promised to get a tattoo of her on his chest if she took him back.
But Susan wasn’t having any of it, branding him a “scumbag” as she accused him of cheating on her.
Jeremy, who previously had an X Factor 2017 singer on the show, asked her: “If he’s a scumbag why are you doing to him what you did last night?”
Susan hit back: “I did not have sex with him. He had his d*** in my p**** for approximately one minute.”
Jeremy was seen covering his face in shock as Gary flew into a rage at what his ex had said.
It was then revealed in the lie detector results that Gary had actually cheated on her, but Susan passed with flying colours.
Gary said: “I’ll see you back home. She’ll text me for one later.”
One fan posted on social media during the hilarious exchange: “She had it in her WHAT?”
Another added: “Where did she have what?”
Jeremy Kyle continues tomorrow at 9.25am on ITV.