Caitie Mae from Dallas used to have a blog where she spoke of the gag reflex causing additional saliva to make it a wetter BJ. But she never suggested taking it to the level of vomitting.
The thread pmdelites referred to was pretty disgusting, in my eye.
I did have a lady once who wanted me to 'face fuck' her for want of a better description. We started out with me on top, but I was afraid I would hurt her. Went to me on my back and her on top, as I grabbed the back of her head and pounded pretty hard. At least that way she had a litttle more control if she needed me to stop. She kept asking for more, then suddenly she jumped up and ran to the bathroom for a towel. Turns out she had gagged and vomitted a little. I was surprised, but we both found it kind of hot. Never did it again, and no desire to ever take it that far again, but still kind of hot. Her and I spoke about it in chat back in the ASPD days one night.
Still, to take it to the level shown in that video pmdelites was refering to went way beyond any pleasure for any party I would think.