Looking for Story...

Man inflates lover in a semi-public place on some nature trail (or some such).  Woman is completely under man's control and he keeps teasing her about letting her float away.  I want to say it was an hourglass inflation with a repeated emphasis on her nether region.  In the end the man lets the woman go and she floats higher and higher and explodes.  Story is told from the woman's perspective and she keeps mentioning some hiker/jogger nearby who she knows is watching the whole thing.  Any thoughts on where this story is?  Thanks.