Thanks for the clip around the ear, Panic: enjoyed the physical contact. However, a 'spoonerism' is an accidental or purposeful { for the intent of humour} misplacing of initial letters of words in a phrase or statement. The classic example is: "You have hissed the mystery lesson" meaning "You have missed the history lesson."
spoonerisms that work aurally don't always work on paper - as with the word botching/wird batching one, but as most spoonerisms begin life through accidental slips of the tongue, i thing the aural ones work the best
the name spoonerism, came from a man, called spooner, who many years ago unintentionally became well known for doing this.