"We're Waiting For One More Volunteer"

. . . and the very snooty boarding agent continues her threat of not letting us board. She actually said "The clock is ticking." What does that mean? Like the plane is gonna take off empty if we aren't boarded in time? [And as a complete sidenote, all you Ticket fans out there might want to take a look at this from Saturday night. The rest of you won't understand so don't bother.]