It looked like a diet coke so the sugar substitutes MAY help slow that process, still this was cute. Doing odd stuff with your partner is a lot of fun, I would never have thought to play with soda though. I figured it would burn, like it does your throat when you drink it.
Pretty hot to find a woman willing to do this. But I think the best way to get best results. Is 6 or so mentos deep in her asshole. Then find a big culinary syringe that can hold at least 16oz . Then insert syringe and push the whole 16oz in as fast as possible. And I'm sure it will come out twice as fast