My sister and I often visited my mother, usually separately - my sister lived nearby, and I looked after work. My mom had two identical cups, both of which we preferred to drink tea. One day my pregnant sister saw that I drank from the same cup and burst into a long monologue, the whole essence of which was that I could infect her with something. Then she marked her bowl with a piece of blue insulator on her chest and in a strict voice ordered for nothing, under no circumstances, to use the fluid from her bricked dishes. Later, my mother told me that her sister sometimes glued the insulator because she was lazy to wash her cup.