I was just reading this article (about an exhibition examining the history of English) in which I came across the word spoonerism. What’s a spoonerism? I instantly headed on to Wikipedia.

A spoonerism is a deliberate or accidental error in which corresponding parts of words are switched. Examples make this clearer:

• Go and shake a tower (take a shower)
• A blushing crow (crushing blow)
• A bat flattery (flat battery)

My personal favorite example by miles:

The Lord is a shoving leopard

(a loving shephard)