I have seen similar transcripts in the USA ( O´Hare is a good location for that) they are the product of a few individuals that exorcise their stress by using those " triying to be funny" expressions.
As Heathrow Director rightly said, stress affect people in different ways. I have seen people staring and leaving long silences after each transmission, Now that is very scary if you seat beside such a person, but it does not look " good" in a transcript and in the news.