I was messaged on Tinder by a girl [7/10] to have a threeway with her and her boyfriend. The message stream goes:

Girl: Interested in a couple?

Me: depends on what you mean by couple

Girl: gf and bf

Me: you're going to have to explain

Me: you and your bf are looking for another M?

Girl: Yes

After laughing for a good minute at how absolutely cucked you must be to let your girlfriend proposition strangers over the internet to fuck, I started thinking. Either this is a gay thing, or this is a girl who convinced her bf to have a MMF threeway where she gets to fuck another guy because he's beta. I'm not into the idea of double teaming a girl, but watching the female id play out so viscerally is an experience I'm having a hard time passing up.

What should I do, pass and continue on my merry way, or bone a girl while her bf watches? Ignoring moral arguments, that answer is clear.