Here are five phrases people misuse all the time that can instantly make you sound dumb . . .
1. "For all intensive purposes." The correct way to say it is, "For all intents AND purposes." "Intents" as in intentions.
2. "I could care less" should be "I COULDN'T care less." If you COULD care less, that means you DO care about something. If you couldn't, then you don't care at all.
3. "One in the same" should be "one AND the same." It's a minor difference, and you might be able to get away with it. But technically, "one IN the same" is wrong.
4. "Tongue and cheek" should be "tongue IN cheek." It's literally describing a facial expression people make when they're joking. Like if you were trying not to laugh and pushed the side of your cheek out with your tongue.
5. "Jive with" should be "JIBE with." "Jibe" means to be in agreement with something. "Jive" is a type of dance, or a way of speaking. (Like the old woman who speaks jive in the movie "Airplane".)
People started using the word "jive" in the 1920s. And according to Merriam-Webster, they started confusing it with "jibe" almost immediately. So don't worry too much if you mess that one up.