When people engaging in sexual activity swallow too much cum or sperm and get a belly ache.
When I had sex with my girlfriend 6 times yesterday, all that swallowing gave me a total cum tummy today.
CUM TUMMY IS WHEN YOU ARE BANGING A TRAMPS TUNA CAT YOU PULL OUT CUM ON HER GUT AND USE YOUR COCK LIKE A PAINT BRUSH AND WRITE THANK YOU WITH YOUR FRESH LOAD!
I WAS SO THANK FULL FOR THE SUPER TIGHT SNATCH I REWARDED HER WITH A CUM TUMMY!
Noun: Is used to describe a very sexy stomach on a pretty woman, when a man wants to cum all over her stomach.
Man did you see Crystal? She's got a nice cum tummy. I'd bang her all night.