Jizzervoir
When a man pulls out during sex and ejaculates into a girl's belly-button, filling her belly-button up with a man-made lake of jizz.
Tony and Jane were having sex in the missionary position. Right before he reached climax, Tony pulled out and filled Jane's belly-button with his ejaculate, creating a reservior of ejaculate in her belly-button. Jane proclaimed, that is a jizzervoir.