Spoonerism 601 Words You Need to Know
an unintentional mistake in pronouncing two words in succession in which the first sounds of the two words are exchanged humorously, accidental verbal error, slip of the tongue, gaffe
A spoonerism is an error in speech in which corresponding consonants, vowels, or morphemes are switched between two words in a phrase. These are named after the Oxford don and ordained minister William Archibald Spooner, who reputedly did this.
While spoonerisms are commonly heard as slips of the tongue, and getting one’s words in a tangle, they can also be used intentionally as a play on words.