If you bring milk for your coffee to work and leave it in the fridge, it's safe to say all of your coworkers will help themselves. Unless you do something this extreme.
A cop in Halifax, England took a picture of the inside of the fridge at the station where three different people have special locks on their milk. A bar goes through the handle, into a plastic cover over the milk, and it's padlocked.
They're homemade? So if you want one, you'll probably need to study the picture and head to Home Depot for supplies.