I don’t have many, but here are some:
“Which begs the question…”
Begging the question is a logical fallacy, not an obvious question. Read wikipedia.
Toothpaste. Not toothpaste in general, but the way people tend to use it. Toothpaste tubes are meant to be squeezed from then end, not the middle. It makes them work better, and makes everyone happier. I’m stunned by the number of people who do this.