A malapropism is the use of an incorrect word in place of a word with a similar sound, usually with humorous results. It's named after Mrs. Malaprop, a character in Richard Brinsley Sheridan's play *The Rivals* who was known for her misuse of words.
For example:
* "I'm going to the pharmacy to get some medication" instead of "I'm going to the pharmacy to get some meditation".
* "He's a very intelligent man" instead of "He's a very incompetent man".
Let me know if you'd like to hear some other examples!