eat one's own dog food

verb2

1. •
   To use or consume the economic goods or services that one is producing; to be part of a closed household economy.
2. •
   (slang) To use products or services one is selling internally, in order to understand their limitations.

   • AOL was signing up members at a furious rate, in part because it provided a better user experience than Juno, and we didn't understand that, because we didn't eat our own dog food. — 2004