What happens when you try to card (potentially underage) kids

I work in a gas station, this is one of my favorite WTF encounters with a customer.

Three kids come in and all are looking at/talking about the tobacco and what kind to get. Since they were all talking about it, I have to card them all even though they are only getting one thing.

Only one of them has their ID, when I try to explain that I need all their IDs, the other two pull out their smart phones and say "Hold on, I'll show you my birth day on Facebook."

REALLY!?