My favorite blue pen vanished last Tuesday, and I found it in the break room with a bite mark. At this rate, I'm gonna need a GPS tracker for my stapler. Maybe we should just install a lending library with a check-out system... or you know, people could actually ask.
Nah it's still rude honestly. Borrowing without asking just shows you don't respect other people's stuff. Returning it doesn't fix the first part, especially for personal items.
Honestly, I see where @king.victor is coming from. In a lot of workplaces, people borrow pens and stuff without asking all the time. It might just be a habit from seeing the office supplies as shared for the whole team. If they return things, it shows they're not trying to steal but just get work done quickly. Making a big deal out of it could create tension over something small. Sometimes people are busy and grabbing a pen feels like no big deal. As long as it's not your special items, this kind of sharing keeps things moving.