look up any word, like darude - sandstorm:
 
1.
The act of engaging in intercourse, to climax or not, with the umbilicus/navel/belly button. It frequently occurs in inexperienced males that are seeking any dark crevice for sexual pleasure while lacking in knowledge of the female anatomy. It can also be intentional, especially when the sexual act involves a partner, male or female, with a significant amount soft tissue is present in the neighboring structures. It is not to be confused with coitus panniculus, engaging in coitus with the folds of abdominal fat.
I was unaware of the female anatomy my first sexual interaction. While searching for home, I engaged in coitus umbilicus as she writhed from pain as her happy trail was mechanically stripped of hair from the friction.
by William Black July 12, 2013