In agile project management, you have frequent meetings of the project team (usually daily). The goal of these meetings is twofold:
These meetings are designed to be short, and agile methods like Scrum suggest that you ask everyone to remain standing during the meeting. Fifteen minutes should be a reasonable meeting length.
In order to keep these meeting short, the only people who can speak are people who have obstacles or information that others need to take action on. The key word is action. If information isn't salient for 'right now,' it shouldn't be discussed in this forum.
The people who can speak are 'pigs.' Other stakeholders may attend but they should not speak (much). These people are called 'chickens.'
The terms 'chickens' and 'pigs' comes from the statement: "In a ham-and-eggs restaurant, the pig is committed but the chicken is simply involved." Numerous versions of this statement exist as jokes or humorous anecdotes.
Why define this again? I went looking for a good definition of the "Chickens and Pigs" metaphor and my search didn't turn up a lot of useful hits, so I thought I'd add my own definition that I can link to.