If you see one of these in a public restroom you need to call the police.

Police have issued a terrifying warning about a certain type of clothing hook that is popping up in public bathrooms. At first glance, nothing seems suspicious, but upon further investigation these hooks contain a hidden camera used for filming people. [Source]

Here's what they look like:

Police have even go so far as to issue a public warning about them:

The scariest part is that these hooks can be bought on sites like Amazon for as low as $13.  So if you happen to see one, you should leave the area and call the authorities immediately.