A new team member joined us today. After introduction, he grabbed a chair. F*** YOU, IT'S JUST YOUR FIRST DAY BUT YOU'D GRAB KATE'S CHAIR WHO JUST TOOK A COFFEE BREAK?! PET PEEVES I HATE CHAIR GRABBERS

Did he not get a chair assignment ceremony then?

Somebody took a chair that was nearby and that’s a fucking pet peeve? Thank god I don’t work with anal retentive folks like you.

You could politely mention that someone is sitting there and will be back in a moment. Then suggest a chair that either isn't being used. Here's hoping that vein popping out of your head doesn't burst when a real problem arises...