A malapropism, or a Dogberryism, is when someone uses an incorrect, but similar-sounding word in the place of the correct word, often to humorous effect. In fiction, the use of a malapropism often shows a character to be poorly educated and/or lower class. The term malapropism comes from the 1775 play, “The Rivals” by Richard Sheridan wherein a Mrs. Malaprop often says wrong, but similar-sounding words to what she means. For instance: “Sure if I reprehend any thing in this world it is the use of my oracular tongue, and a nice derangement of epitaphs,” (Act 3 Scene III). Malaprop comes from the French-derived word “malapropos” meaning inappropriate.
“You have hissed the mystery lectures,” when someone, “you have missed the history lectures.”
This is not a malapropism, but a spoonerism. A spoonerism is when the initial sounds of two words are switched.