When there's a physical good being sold, and not an electronic good, chargeback fraud is too easily disputed by the merchant. My guess is that they were using someone else's credit card. But what doesn't make sense is why 150 pizzas? Such a large single transaction would be too easy to flag as possible fraud, especially when it's originating from a country or state that the cardholder doesn't live in.
I would have simply told that you will gladly fill his order for 150 pizzas, but you would not be able to take a credit card for the purchase. It would need to be cash.