Plug Coffee Mug / Cup
This is a simple mug / cup but with a hole in it, which renders it completely useless to mug thieves. Just keep the plug safely stowed away.
Sometimes it starts as an innocent mistake, shall we say a case of mistaken identity. You go to make your morning coffee, and your beloved mug is not where it should be. The following week you go to the kitchen and your mug is lying abandoned in the sink with green tea stains all over it and you don't drink green tea! Before you know it, your mug has been round the office more times that the mail trolley, and has become home to more varieties of beverage stains and lipstick marks than is proper for a decent mug.