A sarcastic expression used when a person uses the word "we" when they should have actually Used the word "I." Or when a person says that "we don't" do something that at least one person is actually doing. This expression is used to totally catch the offender off guard, rendering them incapable of coming up with a response to the awkward comment.

When you eat dirt for the first time and leave your family to build a shack in the woods