I think this is definitely an area to expand on; cream-pies and dripping would be nice, as would even a simple aiming mechanic (click backside, stomach, chest or face for example).
I think that more fun would be the option of sloppy-seconds; i.e - cumming and then carrying on (if you have enough blue-bar left), gives you a chance to make a real mess before you're done, it is a fantasy game after all!