Negroes, mulattoes like to spank white girls in all holes. The fact that this brunette is also a charming girl - gives a glamour to what is going on. And he's just using her as a device to jerk off his dick and lick his balls. He uses it and then he flushes it. And she's satisfied.
What a sweet surprise that turned out to be, and the wife is good, she knows what to ask for and how to satisfy everyone when you three together. Wouldn't mind being in that friend's shoes myself, I would have had my ass up her ass.