On a more general tack, but prompted by the OP and succeeding two posts: Ive long found this sort of goonery indulged in by a minority of railway enthusiasts, irritating and not primarily because of the danger factor sometimes present, as in the scene in Cowleys picture. I would reckon that its been around for a long time: human nature being what it is, probably as long as the hobby has existed...
This sort of caper-cutting most often, involving getting into grotesque physical attitudes and positions tended especially when I was younger, to make me, in person a fairly introverted and subdued type, feel somewhat nerdish and dull and generally inferior (not that I actually wanted to perform these idiot cantrips). Its stuff that some people do, especially some males attempts to impress the female of the species, no doubt part of this bag of tricks (though on the overwhelmingly male gricing scene, that would seem to be wasted effort). Ive always felt that hobbies should be potentially, a pleasant refuge from some of the more aggressive and competitive facets of human social behaviour: diverse individuals united by their shared interest in a particular subject, rather than trying to in various ways out-display, and put down, each other. People being as they are, though; this stuff appears with some frequency, on hobby scenes too including the rail hobby.
Ive been to slide shows, supposedly about visits to interesting rail venues; where the presenter clearly thought it good, to have a considerable number of his slides showing, instead, goonish extrovert members of the visiting group performing goofy antics. My reaction to this being: Oh, Lord, I want to see pictures of, and hear about, this particular railway scene not to have the valuable time for that, wasted by stuff about show-offs doing this kind of cr*p.
. I shouldn't think you're the only person on the entire forum that did it either.