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Amy says that boiling water kills germs so it’s hygienic, but one time I found a hair in my mug

Amy and I have been friends for 15 years and have lived together for seven. We’re both big coffee drinkers, but we make it in different ways. We live in Ohio, where it can get very cold, so every morning we like to heat up our mugs before putting the coffee into them. This helps to keep the coffee warm.

I wake up earlier and go to work first, so it was only fairly recently that I learned that Amy warms up her mug every morning with boiling water from the kettle. But after the mug has warmed up, she pours the water back into the kettle. It bothers me in a visceral way. It’s like double-dipping a chip or spitting wine back into the bottle. It’s just gross.