Loaf of Bread/Loaf of Cake

Below is one of the stories Grandpa Peter would love to tell . . .

I was working in a grocery store in Brighton, and every day I would see a woman walking by hitting her son over the head with a loaf of bread.  But one day, she walked by hitting her son over the head with a loaf of cake.

I rushed out of the store.

"Lady," I said. "Every day you walk by this store hitting your son over the head with a loaf of bread.  But today, you're hitting him over the head with a loaf of cake.  How come?"

"Oh," answered the lady.  "It's his birthday."