A question about female uality (not suitable for minors)?

When our lecturer made a joke about male masturbation, my cl immediately showed 2 very different emotions, absolute disgust from my female peers, and humor from my male peers. I don't understand why females find men masturbating horrifying. My ex show a similar expression as someone producing a turd right in front of her when she saw me masturbating. But when I saw her doing it I was hugely turned on. Why don't most women find men masturbating attractive?