What is why do women sit on washing machines?

It's important to state upfront that there isn't a widespread or common practice of women routinely sitting on washing machines. The premise of the question is not accurate. However, here are some potential (and speculative) reasons why someone might sit on a washing machine, regardless of gender:

Important Consideration: Sitting on a washing machine regularly could potentially damage it, depending on the person's weight and the machine's construction.