It's a primate thing...other primates besides humans have been known to enjoy watching others in their troupe screw around as well. It's about status, power, control, affection, carnal pleasure and living vicariously through that I think.
You get to see plenty of other attractive woman nude & what their bodies look like compared to that of either your partner or just for looking at for any other reason. Also what their pubic hair colour is & if they have any at all ? I prefer those that look young & are slim / petite / short / medium build but not overweight looking & show as much as they want of their body. The more they show of their genitals / butt / the more turned on I get.
