This is, (and correct me if I’m wrong), a vocal sound people make, which is more accurately sucking one’s teeth. You press your tongue against your teeth and by sucking make a ‘Tschioak’ sound. It’s an expression of impatience, or disapproval, or disgust.
Now I’ve heard white folks from Iowa use the KMT sound, apparently in the same way it’s used in the UK, Jamaica and elsewhere. But I’ve never heard of it having a name; apparently it’s such a commonplace in the UK, that the acronym is instantly recognizable.
I have no insights about this at all; this is more of an Andy Rooney observation.
“Trisha” is on UK TV, and the joke is apparently that ‘she’ is Jamaican. This video makes it look as though “Kiss My Teeth” is one of Trisha’s catch phrases.