I know that face. It's the "Mister TA, I need the potty pass now!" look. When encountered, the potty pass must be provided immediately, as young'ns have a nasty tendency to wait until the absolute last moment. And don't even get me started on the abject terror a chaperone faces when one of their charges makes that face while the gods and goddesses thrice-damned van is still several effing minutes from the nearest gas station. Oh, ye GODS... And then to top it off, EVERYONE starts needing to go. And then you have an effing LINE outside a single dirty ol' gas station bathroom...! The horrors... The horrors!
*Thousand-yard stare intensifies.*