[Wife placed online purchase; card was declined.]

Me: Okay, I called the credit card company. They’ve removed the hold.

Sarah: But why did they put the hold on it instead of letting me shop?

Me: The customer service rep doesn’t know anything about that. It’s some crazy algorithm that some mathematicians developed for them…

Sarah (indignantly): What? You’re blaming math?

Me: No, I —

Sarah: “Math is hard, let’s go shopping” — oh wait, I can’t!