Can’t Touch This
These kinds of notes ignite a fire in staff when you see them. The audacity someone must have to print out a whole note that sends a message not to “touch” their stuff seems a little bit much. It sometimes just takes a quick verbal reminder to others that certain things are yours and you prefer them not be used.
Maybe someone was just very thirsty and couldn’t find their own cup. Maybe they assumed there were multiple mugs available to all staff to use and they weren’t sure which were personal, and which were shareable. You could rub people the wrong way with notes like this and you might get a passive aggressive note right back at you.