This is a good lesson to learn. ChatGPt and other LLMs are not search engines. They don't know stuff. They sort of guess, with implied authority.
So, no, Chat GPT is completely wrong. Not "The Sketch Show", which was a very bland ITV early evening thing , not all like the surreal Big Train.
The Sketch Show is such a wrong answer to that question that it made me do a Google AI search to see what other bollocks an LLM might come up with. It said this:
"The specific sketch you described involves comedians in a "last one laughing" competition, where they must make others laugh without laughing themselves.
The Sketch: A contestant introduces another comedian (the man) to his "long lost mother." The mother is a tiny, old, wizened woman who walks over and intensely licks the man's face with a comically long, prosthetic tongue.
The Context: It is designed to be disgusting and shocking, which fits your "so rank but at the same time so hilarious" description perfectly.
Katherine Parkinson: While she was not the one licking in that specific sketch, Katherine Parkinson is a prominent figure in British comedy (known for The IT Crowd and Here We Go), and her reactions and comedy style are often highlighted in similar British sketch/ensemble contexts.
You can find the clip on social media, often titled "Tongue Talk | LOL: Last One Laughing"
Please learn from this, everyone! Chat GPT and LLMs CANNOT BE TRUSTED!! They get stuff. COMPLETELY WRONG and too many of us are beginning to rely on them. It really doesn't matter when you're trying to remember the name of a TV sketch show, but imagine if you were asking something important!