"When ingested, carbonated beverages have been shown to release its gas into the gastric lumen, causing distension of the stomach. This distension is thought to increase gastric emptying rates, which would consequently affect alcohol absorption rates." Journal of Forensic and Legal Medicine 14 (2007) 398-405
I wonder if carbonation also plays a role in protein the rate of absorption because, like alcohol, it is absorbed in the small intestine. Maybe this is why Jay drinks pop with his after workout shake???