(F4M) It's your birthday and we invite my friend over for an evening in the hottub

It's my BF's birthday and you've literally been counting down the days until this evening.  It's Friday night and the sun has already set.  You've been so eager to get me in the hottub... alone in the back yard.  The blue lights underwater glow dimly in the darkness, our little private oasis intentionally hidden behind trees and shrubs so that the neighbors can't see.  You've got me in your favorite bikini, the little pink g-string that makes me feel embarrassed and exposed even around just you.

You're used to all this though... you get me in the hottub several times a year.  Kissing me, feeling me up, sex with me bent over the edge.  But tonight is your birthday, and you're getting something special that you've been asking for for months.  We invited my friend Kimi to come swim with us.  I've let you fantasize about her before.  You're a man, so I allow you to behave like one.  I've even talked dirty about threesomes sometimes just to make you horny and get you off.  I know you love it.

But now... now she is on her way.  We haven't suggested anything dirty to her, but we know she is a slut.  She's flirted with you before.  At first it made me jealous, but that's just the way she is and I know you wouldn't leave me.  It would be stupid of me to think you weren't sexually attracted to her, but that's all it is.  

My heart is pounding in my chest as I sit in the water and try to relax.  I look at you and see the big smile on your face as you sit across from me, eagerly awaiting our guest.  I blush and feel a tinge of nervousness and arousal, just from knowing how turned on you must be.  "Happy Birthday sweetie..."  I say with a smile.

A moment later we hear the side gate open and I see you smirk, obviously thrilled that she actually showed up.  I look over and see Kimi appear through the bushes as she walks up the path.  Her pale little body seems to glow in the moonlight.  She has on a little red bikini, the strings of her top are pulled tight as they hold up the fabric over her perky D cup breasts.  I'd feel jealous if it weren't for the fact that mine a just a little bigger than hers.  Down below, her little red bottom clings to her smooth skin.

"Hi Kimi..." I say nervously, feeling awkward to have a third person in the hottub.  I see your smile as your eyes move over her body and she begins to get in the water.

I can tell what you want... I know that you're turned on by the fact that she is a blonde and that she is busty and petite like me.  You've already told me your fantasies.  I've jerked you off while you confessed to the fact that you imagine me and her naked in the hottub, our soft flesh pressed against each other as you tell us to kiss.

Back to reality, I feel adrenaline pumping as Kimi sits next to me and smiles, both of us comfy in the warm water.   "Hi guys, thanks for inviting me!"  She says in an upbeat tone.  I wonder if she can tell what you want.