User tinkerbellthinks shared this photo of a newspaper notice from the Xerox company admonishing whoever would read their message not to use their brand name to refer to the act of "photocopying" because it damages the trademark of that company.
In one of the comments, user Bluenette was reminded of an ad made by Velcro, the company who invented the hook and loop, which also urged people not to use their trademark to refer to their product. So remember it's not a Xerox, it's a photocopy. Don't say Velcro, it's a hook and loop.
(Image credit: Tinkerbellthings/Reddit)