A... threesome? Regulus has certainly made a few leaps and bounds in his category of what is acceptable and what not, BUT. Seriously. He's not even been able to contemplate actually having sex with Barty. Let alone two people at once!
Also, Regulus thinks they shouldn't talk about him like that. He doesn't.. like boys.... Seriously. He doesn't! >.>
But yes, much joy and wonder on our parts to come.