Spoonerism

"One swell foop" is a Spoonerism, "the flaw in the ointment" is a Farberism.

Source: tatoeba (2027730)

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.

Source: wiktionary

A Spoonerism may sometimes alter the whole tenor of a person’s career. An extremely bashful man was asked to find the elderly daughter of the house, who was in the garden, and ask her to make tea. “Miss Florence,” he said, when he discovered her in the rosery, “I have come to ask if you will take me?” And she did!

Source: wiktionary

I am not going to put on any weight until I’m fifty, when I shall allow myself to become matronly, ready to be a follower of ‘soda and gobbly matrons’, as enjoined by the marriage service. (A good Spoonerism that, created quite involuntarily by my mother some years ago.)

Source: wiktionary