[Jr.]

"Could care less"

Simply because it's wrong how it's always used. People say it with the implication that they don't care at all. Well, if you could care less, it means that you do care some. Dummies.

"Lacksadaisical"

Also wrong. I had a big debate in a GRADUATE school class about this word. So many people think there's a "S" in this word, when there isn't at all. It's "lackadaisical"

"Uber"

Just overused now.

"Like"

When used as a filler word. Drives me crazy.