American here. I did a semester abroad in Ireland, and one particularly clueless fellow in our group of students made the mistake of ordering one of these in an (actual) Irish pub.
He was firmly asked to leave - and lucky that was all. I imagine he wasn't the first uninformed tourist to make this request. Years later, I likened it to ordering a "9/11" in Manhattan, although it's not a perfect analogy.
Ordering one in Britain is possibly closer¹, and a bartender I used to live with said clueless, young, American tourists would try this every few months.
They were usually dealt with by referring them to history section of their Lonely Planet.
¹ Several car/truck bombings with considerable property damage, although usually limited casualties.
Yeah most people would find it in poor taste. No point in ruining a perfectly decent pint of Guinness. The comment you were replying to was referring to the "Lady Boy" drink from Alan Partridge.
https://en.m.wikipedia.org/wiki/Irish_Car_Bomb