A spoonerism is an occurrence of speech in which corresponding consonants, vowels, or morphemes are switched between two words of a phrase. These are named after the Oxford don and priest William Arch
An example of spoonerism on a protest placard in London: "Buck Frexit" instead of "Fuck Brexit"
Caricature of Charles H. Workman. The accompanying biography reads, "The only part of him which gets tired is his tongue, and occasionally the oft-repeated lines have got muddled. 'Self-constricted ruddles', 'his striggles were terruffic', and 'deloberately rib me' are a few of the spoonerisms he has perpetrated."