I recall Rush Limbaugh used “flummoxed” a lot.
A few years ago I used flummoxed in conversation with a friend who apparently considers her vocabulary very extensive. She said she’d never heard the word, and asked me what it meant, so I told her. Then she looked it up on her phone to check me. A few minutes later, she said something like, “well who’s the smarty pants now? You were right! It is a word!”
P.S. I’m not sure where I heard the word first, but I was taught by Irish nuns, so maybe that was it.