We saw some time ago that if somebody invites you to a meeting in Building 7, they are inviting you off campus to take a break from work.
If somebody invites you to a meeting in Building 109, Conference Room A, they are inviting you to join them at the Azteca Mexican restaurant next door.
Update: One of the members of the "Building 109 Conference Room A" mailing list informed me that Building 109 Conference Room A is specifically the bar at the Azteca restaurant.
Update 2: Building 109 Conference Room A has its own mailing list!