If my husband said to me, "Do _______ to me like (ex girlfriend) used to do," yes, I would be upset. If he just suggested a certain type of sex play I don't care where it came from- ex girlfriend, porn, an urge, or a conversation from the guys. If it's doable for me, I'd do it. Personally, I like to know what he likes.

In all fairness she only told you she heard this from an ex because you asked. You've had sexual partners before her, yes? You've never reused any moves from previous experiences? If so, was it because you knew you like it or was it because you were fantasizing about that person or feeling your partner at the time was inadequate?

Her specific request isn't an unusual one either. My husband says it to me from time to time when he's really worked up. It turns me on for that reason. I've read it in books, too, so her request could have come from anywhere.