Ok, so this is what happened. I was sitting outside and I opened up a diet coke. It was fine for several minutes and then out of no where it just started fizzing up. It was almost like dropping a mentos into it but not so violently. It eventually got to the point where there was no more carbination in the soda at all. What I would like to know is how this can happen. As far as I know nothing fell into the drink and it was completely fine before it started fizzing.