These are words you probably hope you will never say: "I finished shredding my dad's sex diary today."
You also probably do not want to say, "I shredded the photos of them naked yesterday" and your wife does not want to say, in response to your saying, "They didn't look that ba----," ""STOP!"
Your wife does not want to hear any defense or any description of your parents without their clothes. She does not want to hear about your dad's sex diary and sex in your sister's bed, although in your defense, you did not want to read about it, either.
You probably also hope you will never say, "I read a little bit every few pages as I was shredding. It doesn't look like they ever had sex in my bed."
You don't want your wife to ask, "Are you a little bit insulted by that?"
You don't want to answer, "Well, my sister did have a waterbed."
You do not want to have a conversation like this at all.