Years ago I worked for someone who ran their business out of a home office while they were establishing themselves. I didn't have a proper desk, often just sitting inside the spare office with a laptop if his wife wasn't working as well. If she was, I would have to sit inside the house at the dining table. I had to use their kitchen for lunches and there was a small wash closet in the laundry, I didn't love being in their personal space so much but it was a flexible job that I was good at.
Anyway, one day the wife comes out to me and says that she's noticed I boil the kettle a lot (I drink about 5 or 6 cups of green tea a day) and could I only fill the kettle with what I needed because I was racking up their electricity bill. I was so fuming, because she was a real tight
a, when they lived in this big beautiful home and even had a pool installed while I was working for them (they kept saying they were holding off on renting an office until the business was making enough

yet could afford a pool). So every time I made myself a cup of tea, I made sure the kettle was full to the brim before boiling it. Still the pettiest thing I've ever done haha