Well you will have to run that by the girlfriend first and if she is game I would think she might be the one to run it pass little sis! Good luck sounds like you could have some real fun! lol
I do think however that it is very remote that they are going to go along with this.
If you tell her keep us posted on the results but I don't think it's a good idea... That might make her feel uncomfortable that you have the hots for her sister and plus who wants to go down on your sister? That's incest.
Haaaaa. good f***ing luck. lol.
Do you not care about your girlfriend, whatsoever?
This will not only hurt her, but your ass is getting kicked to the curbbbbb.
I'm going to tell you right now this isn't going to happen and if it doesn't you can kiss your relationship goodbye. Nobody is going to be comfortable with their sibling sleeping with their SO. This is one of the p*rn scenarios that just isn't real.
would you do a threeway with your brother?
this is one fantasy your gonna have to keep deep down in the spankbank my friend
BA
BA +1
Scroll Down to Read Other Opinions
What's Your Opinion? Sign Up Now!HA! unless you don't want a girlfriend anymore, I wouldn't mention it if I were you.
Unless your girlfriend is into that sort of thing, which I doubt.
I highly doubt she would have a threesome with her blood relative. Maybe a mutual friend or something. I wouldn't get your hopes up and that might be a can of worms you might not want to open.
so you want to see them play with each other?
Wouldn't that be incest if her SISTER was dragged into it?
It's not his sister!
If each of them was having sex with him, but not each other, it would not be incest. Weird, maybe, but not incest.
What makes you think she wants to have sex with her sister? Unless she has hinted at it, keep it as a wanking fantasy only.
I don't recommend you taking the risk to ask them to do this. Only if they ask you first. You girlfriend might think that you are sick for thinking about doing that, and it will be the end of you two. Don't risk it.
You can tell her... be straightforward...
ask your girlfriend. my girlfriend did a 3some with her sis and her boyfriend. they loved it. my girlfriend is bi but her sis isnt, or at least wasnt. can't hurt to ask, lol.
explain your girlfriend about fun in threesome...slowly she will into it..and hopefully you get chance to f*** both of the sisters...take it as experiment...then she will be in line I think.
it won't work out
The closer the kin, the better the skin
This is incest and illegal.
Well, first off you girlfriend might have no interest in a threesome in the first place. If she is interested she might want it to be her and two guys. If she was find with you and another girl, I highly highly doubt she would want her sister to be involved. There is probably a 0.0000001% chance of her wanting her sister in her 3 way. You could try asking her and/or her sister, but odds are it would go bad and you would be kicked out. Why not suggest a different girl in the threesome?
The chances of this happening are slim.
Assuming she's legal and slim, most of us would like to have sex with our gf's younger sister.
Its not happening.
First, slide into a parallel world, where p*rn storylines actually happen in real life...
Sexual Relationships 
Sexual Health 
Most Helpful Girls