An individual who, in secret, defecates in a location other than a toilet, for the purpose of creating humor and/or havoc. The practice is more common anywhere large collections of male humans cohabitate, such as in college dorms and military barracks, but may occur at any time, in any place, regardless of the demographics of the locale. Naval lore suggests that the practice dates back to World War II.
"The Phantom Shitter has struck again"
A prime example may be found in the first ten minutes of the film "Flight of the Intruder" when the Phantom Shitter strikes the XO's ashtray.
In a pornographic film, or in real life, when the male's scrotum is long and loose, and is riding a female hard, the balls will slap against the female's body, created an additional slapping noise, hence, the bonus ball slap.