The actor, who recently reprised his role as Reg Holdsworth for a spinoff DVD, appeared alongside ex-Corrie stars Julie Goodyear, Tupele Dorgu and Phil Middlemiss to celebrate the ITV soap's 50th anniversary.
The Sun reports that Morley passed wind, burped, spat and insulted his guests in the episode - going as far as to tell Dorgu that he thought she had come from an "escort agency".
The actress, who played Kelly Crabtree in the Weatherfield drama, said: "He's dribbled, I've been spat at and he's farted. I never thought anybody could be so rude, offensive, insulting or inappropriate as Ken."
Despite insisting that his behaviour was "quite normal", a source added: "There's been all sorts of behaviour on Come Dine With Me, but this beats the lot."
Middlemiss commented: "A lot of people would be offended by Ken, but does he care? Not really."
Come Dine With Me: Coronation Street Special airs on December 6 at 9pm on Channel 4.
> Click here for our recent interview with Ken Morley and Kevin Kennedy