I refer to your post about people stealing your mug at work. At the time i knew there had to be a way of solving this problem without having to hire a private detective, killing anyone or disrupting your normal day to day routine too much.
When you leave your mug you just take out the little plug “en siedaar“, nobody can use your mug, which reduces the chances of it being stolen with almost 100%. Of course, you will always find people who would try and steal it anyway, simply because it’s a novelty.
I sincerely hope this helps!!!