Malapropism

Unintended violation of standard diction or grammar which mistakenly uses a word in place of another that it resembles; the effect is usually comic.

The term derives from Mrs. Malaprop in Richard Brinsley Sheridan's comedy The Rivals (1775), who in the attempt to display a copious vocabulary said things such as

"A progeny of learning," "as headstrong as an allegory on the banks of the Nile," and "he is the very pineapple of politeness."

Remember bhabhi ji in Bhabhi ji ghar pe hai. She uses malapropism in her speech.