A verbal error in which a speaker accidentally transposes the initial sounds or letters of two or more words, often to humorous effect.
I learned this word after discovering Rindercella (look it up). Named after the Revd W. A. Spooner (1844–1930), an English scholar who reputedly made such errors in speaking.
“He called me a cupid stunt and it took me three hours to work out it was a spoonerism.”
“Ronnie Barker was particularly fond of humorous spoonerisms.”