Eating your own dog food or Dogfooding in technical parlance means the software maker uses their own software thus appreciate its strengths and weaknesses (and hopefully improve on those.)

Usually I dogfood multiple mobile phones running early releases of Cyanogenmod and Firefox OS. Doing this is easy when you have multiple SIM cards. But if you have to swap your SIM card between Nexus 4 (micro-SIM) and Firefox OS device (mini-SIM) then you'll love this inexpensive Nano SIM adapter from NooSY.

http://playingwithsid.blogspot.com/2014/10/micro-sim-card-adapter.html