Ass In Ambassador: Sometimes – rarely – but usually intentionally.  Which is to say, usually when dealing with those states who keep insisting that the Empire should, y’know, punish people for exercising their freedom of speech, or extradite people for committing something that no-one there would recognize as a crime, or make them respect them, or some such, with a degree of repetition which makes it clear that they’re not going to take “We don’t – and can’t, moreover – do that sort of thing” as an answer.

Granted, sometimes it’s intentional in a different sense; to steal an example’s example from the Discworld section of the trope page, the Ministry of State and Outlands would find sending the equivalent of a Mossad agent and a transvestite as attachés to the Ambassador to Iran – a country which hits a truly remarkable number of the notes guaranteed to make them detest it absolutely – utterly hilarious.  And other necessary qualifications aside, if they could find a female candidate with multiple doctorates, a taste for neat whiskey and fast cars, and the ability to kill a man with her pinkie in eighty-seven separate ways to post to the embassy in Saudi Arabia, they’d do that, too, and enjoy watching the host nation struggle to be polite.  (After all, given the kind of society they are, they don’t think it’s possible to have healthy relations with people like that, so what the hell.)