To use one's own product or service. Originally applied to software companies using their own software in-house, the meaning can extend to any situation that might impose some burden on customers, clientele, constituency, co-workers, etc.
Sen. Chuck Grassley (R-IA) proposed an amendment requiring members of Congress and their staffs to buy health insurance on the exchanges they are setting up, forcing lawmakers to get insurance the same way some of their constituents will. In some circles, this is known as "eating your own dog food."
A (historical) example of -not- eating your own dog food would be Microsoft developers using IBM's OS/2 operating system while developing Windows software because it was more stable than their own operating system (Windows3.1 and Windows 95 at the time).
A new add-on to the ever so classic burn list. It now goes like this:
you
your face
your mom
your mom's face
your mom's face on a good day
your neighbors dog
you are my neighbor's dog
random, yes. stupid, yes. fun to use to piss people off? yes.
p1: You are a fat stupid hobo.
p2: You are my neighbors dog. OHHHHH