What is a malapropism?

From Wikipedia (you'd think they are paying me for all the advertising I do for them) -
A malapropism (from French mal à propos, "ill to purpose") is an incorrect usage of a word by substituting a similar-sounding word with different meaning, usually with comic effect. The term comes from the name of Mrs. Malaprop, a character in Richard Brinsley Sheridan's comedy, The Rivals (1775), whose name was in turn derived from the existing English word malapropos, meaning "inappropriately".

Examples-

• "He's as headstrong as an allegory on the banks of the Mississippi." (i.e., alligator)
• "He is the very pineapple of politeness." (i.e., pinnacle)
• "He missed that field goal by a microcosm." (i.e., micrometre)
• "I've gotta consecrate myself on this newspaper." (i.e., concentrate). (All in the Family) (*Note the non-standard use of the reflexive, indicating the Yiddish-German influence on New York City speech.)
• "If I reprehend any thing in this world, it is the use of my oracular tongue, and a nice derangement of epitaphs!" (i.e., apprehend; vernacular; arrangement; epithets)
• "Then he laid prostate on the ground." (i.e., prostrate)
• "I resemble that remark!" (i.e., resent)

The funny thing is I read up on this word awhile ago when I was bored. Months later I was in Starbucks and the people behind the counter are like, "Would you have any idea what the word is for when you use use a word for something but it's incorrect but it's similar to the word you are looking for?" My face lit up and I said, "Well, actually I do..." and gave them a whole history of the word and they looked at me like I was a freak.