Yes I've heard of this, only with coke or other sodas.
The theory is that the sugary soda will be an insect deterrent (by sticking to the leaves like flypaper, and release of CO2. I tried it once and had to spray with clear water many times to get the stick morass off the leaves cause anything else in the air (dust hair lint etc.) stuck to the leaves also.
I've also heard that using a small propane catalictic heater in the room creates CO2, but in summer that would just raise the temp more.
I supose one could also invite a bunch of freinds over and have a party in the grow room, with everybody breathing heavy at the stripper........ much CO2 could be made=-0