I have a dumb cashier story

Today, when I went to McDonald's I saw on the menu that you
could have an order of 6, 9 or 12 Chicken McNuggets.
I asked for a half dozen nuggets.
'We don't have half dozen nuggets,' said the teenager at the counter.
'You don't?' Ireplied.
'We only have six, nine, or twelve,' was the reply.
'So I can't order a half dozen nuggets, but I can order six?'
'That's right.'
So I shook my head and
ordered six McNuggets
(Unbelievable but sadly true...)