It is Empire of the Summer Moon.
I don't know how many I have talked to over the years on the internet who have played cowboys and Indians and eventually began stripping the victims and, yes, playing with their penises and ass holes. And, not enough times for me, laying the naked victims together. Little did we know, then, what actually happened to the victims. Our new minds couldn't imagine the horrors the victims really went through. For instance, was she dead, yet, when he gouged her eyes out and placed them on rocks overlooking the scene? etc. etc. etc...