My mom’s hack is now just $7. While I wake up every morning craving my daily cup of coffee, my parents won’t touch the stuff.

This provides fodder for fun jabs and inside jokes, but it did get me wondering: Why do coffee and tea stain all my mugs, and why are the stains so hard to get rid of? With these questions in mind ...

Add 1 cup of milk (or adjust for preferred creaminess) and bring it to a gentle boil. Stir in 1-2 teaspoons of sugar (or as ...