Dear Prudence is Slate’s advice column. Submit questions here .

Dear Prudence,

When my in-laws stayed with me and my husband for a week (this was their first such visit), I learned something disgusting about my mother-in-law.

She does not adequately wipe her butt. While doing the laundry, I discovered prominent skid marks on all of her underwear. I was thoroughly grossed out. What’s a tactful way of addressing this with her for the next time she and my father-in-law are over?

—Toilet Paper Is Available on the Open Market

Dear Toilet Paper,

Repeat after me: “I am not going to shame my mother-in-law about her skid marks. I am not going to mention my mother-in-law’s skid marks to her, ever.”

This is just really, really not your business. The state of her underwear either repre

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