A fork of Rural Dictionary
This is during sex when the girl is preferably in a cow girl position. You and your couple are enjoying it when all of a sudden the girl takes an unexpected poop on your lap. The poop is considered the "Siva".
Boy 1: "Dude, you still dating that one chick?"
Boy 2: "No way, i dumped her after she left a Siva on my lap last night."