spoonerism

noun

Etymology: From Spooner + -ism, named after Oxford don Reverend W. A. Spooner (1844–1930), who is supposed to have habitually made such slip-ups.

1. A play on words on a phrase in which the initial (usually consonantal) sounds of two or more of the main words are transposed.

   “Undergraduates at Oxford University were playfully fond of Spooner, whom they nicknamed "the Spoo". They also coined the term "spoonerism" around 1885, after Spooner had been a fellow at New College for almost twenty years. By 1892, his reputation for absentmindedness was well known; students came to New College expecting to hear a spoonerism.”