This is known as ‘the attitude cup’. That’s what Jan was calling it when I moved in with them in 1995. The rule was, it belonged to whomever needed it at the time; everyone else knew to leave the person in possession of the cup the fuck alone.
When Preston and I moved up here in 1999, Jan insisted I take it with me. So I did. She said it was for Preston’s protection and sanity. The ‘attitude cup’ met with an unfortunate accident in early 2000 and lost its handle. I tried gluing it back on, but it kept snapping back off. After that, it lived on my stove until recently. I used it to keep small cooking utensils, bottle openers, and such things handy. All that’s in a drawer now, and the cup is sitting on the counter empty and unused–but not unloved.