from the French mal a propos, which means inappropriate
The mistake of confusing words that sound similar, especially when it creates a humorous statement.
working in tantrum instead of working in tandem
From Shakespeare’s “Much Ado About Nothing” in Act lll Scene 5: “Our watch, sir, have indeed comprehended two auspicious persons,” where Constable Dogberry should have used apprehended and suspicious.
Give it a try. What malapropisms can you come up with?