Deidre Sanders is a firm favourite with This Morning fans thanks to her empathy and kindness.
During a segment where Eamonn and Ruth were talking about Deidre's 40-year career as an agony aunt, Eamonn brought up an embarrassing moment from her past.
Catherine is here so you can apologise to her.
"See I know you're looking at Deidre there and thinking how lovely, how full of empathy, kindness and cuddliness she is," he jokingly told the viewers.
"But Deidre was imprisoned for assault. There was a lovely member of our team called Catherine Hodgson who would do anything for you, she works in production here.
"Rather than let me explain see the evidence that put Deidre in prison herself."
He then showed a video of Catherine in a previous episode accidentally wandering into shot and Deidre shoving her out of the way.
"She was hurtling towards me and I just gently put out my arm just to say 'No you're gonna walk in front of the camera!'" Deidre explained.
Deirdre then got a further shock when Eamonn introduced Catherine, who was working on the show... and another member of the crew re-enacted the moment.
"Catherine is here so you can apologise to her. She's never recovered," Eamonn said.
Catherine joked: "It was not gentle that's for sure."
Earlier in the episode, Eamonn cracked a rather crude joke as he told viewers he was in for a "fun night" with his wife and co-host Ruth.
The daytime TV favourites, both 59, were introducing the segments on today's episode of the programme when they heard the song You're Beautiful by James Blunt, who was due to perform in the studio.
Eamonn said: "It is true you are beautiful, I said play that one for my Ruth. I did, darling. It'll be Friday fun night now, after that.."