My grandmother was a cook, and sometimes she was filmed on TV for a show about mom and baby. Once she showed me a recipe and said, “To do this, you need to take whey oil.” And the leader asks: "What oil is this? I have never heard of it". And the grandmother answers: "This is specially prepared butter. We heat it to a certain temperature, and when we squeeze it in the hand, it between the fingers does so - Vzzkik!"