Eat Your Own Dog Food

Certain less-than-reputable businesses (we're looking at you, Tony Montana) have rules against this sort of thing. Basically, it involves a company that uses its own product.

Legend has it that the term started at Microsoft during the 1980s. So we'll use software as an example. Say a company makes a messaging app. Now say employees of that company use that same app for all their business communications. That's eating your own dog food.

People also apparently say "dogfooding" as a shortened version. That sounds to us like a service offered by some other less-than-reputable businesses, but who are we to judge?