1. To use the product(s) one's company produces or develops as a means of demonstrating or validating its quality, capabilities, or superiority to other brands. Used primarily in reference to software industries, the phrase is thought to have originated with advertisements for Alpo dog food in the 1980s, in which actor Lorne Green promoted the product by pointing out that he fed it to his own dogs. The company sent out a memo to all of its employees telling them to eat their own dog food to demonstrate their new operating system's speed and ease of use.

2. By extension, to use software one's company is developing—usually in its beta form—so as to test it for flaws and ensure its ease of use by end users before it is released. We didn't have time to eat our own dog food before the new operating system's release, so I'm worried it may still have a lot of glitches that haven't been accounted for yet.