If you give your guy direct finger prostate massage...whose idea was it the first time, yours or his?

I wonder how many guys would ASK for this from a partner who had not done it for them the first time?? How would they even ask? Or is it woman who are thinking to add some spice for their guy (or are just curious themselves)??? Just asking.

We did it the first time (I guess it was MUTUAL curiosity) after reading about it a Penthouse Forum Magazine, decades ago.