On the topic of Raj sometimes being the more dominant, I imagine both of them get so turned on by it, cause normally, Wayne is the one who takes charge in their lives, be it in their hockey games or outside of them, so when Raj shows he CAN order and manhandle Wayne around just how he likes, it makes both of them so horny (and happy)

Plus Wayne has an amazing ass and Raj thinks it would be a disservice to not use it.