on the mat
1. In a position to face a reprimand from someone. When my team lost that big client, the boss called me on the mat.
2. Under discussion or consideration. We don't have time to discuss those issues, but don't worry, they'll be on the mat the next time we meet.
on the mat
being reprimanded by someone in authority. informal This idiom is a military reference: the orderly room mat was where a soldier accused of some misdemeanour would stand before the commanding officer.