In The importance of being earnest by Oscar Wilde, a man imagines a person by the name Bunbury, so another man calls that name absurd. Is it really? And why?
My guess is that Bunbury is meant (by Wilde) to sound more like a village famous for its hot cross buns than like someone's surname. A footnote to the word Bunburying in the Wikipedia treatment of The Importance of Being Earnest reports that Wilde used the name as an inside joke:
"Bunburying", which indicates a double life as an excuse for absence, is—according to a letter from Aleister Crowley to R. H. Bruce Lockhart—an inside joke that came about after Wilde boarded a train at Banbury on which he met a schoolboy. They got into conversation and subsequently arranged to meet again at Sunbury.
But on the other hand, in a continuation of the same footnote, another writer concludes that Bunburying has a different source:
Carolyn Williams in a 2010 study writes that for the word "Bunburying", Wilde "braids the 'Belvawneying' evil eye from Gilbert's Engaged (1877) with 'Bunthorne' from Patience.
In any case, when Jack says, "So I am going to get rid of Ernest. And I strongly advise you to do the same with Mr ... with your invalid friend who has the absurd name," he may be reacting in irritation to the idea that his imaginary Ernest is of a piece with Algernon's Bunbury—and in his irritation, he may temporarily have forgotten the imaginary invalid's name and recalled only that it sounded a bit odd. Or he may be exasperated by the idea that he is to some extent going along with the fiction of Mr. Bunbury when he refers to him by his given (by Algernon) name instead of calling him "your imaginary invalid" or something like that.