H1 Should Get This

I read a joke in Reader’s Digest. It seems that a woman was preparing for a party. As the time for people to begin arriving approached, she realized she needed milk, but didn’t have any. She asked her husband to run to the store to get her a quart of milk. He returned a while later, empty handed. When she asked about the milk he answered, “They were out. All they had were pints.” - I don’t get it. Oh, and she also mentioned that her husband is a statistician. – I still don’t get it. (OK. Maybe I do get it)