Ghostwriting a scientific manuscript (e.g., one to be published in a major medical journal). A play on the phrase "ghostride the whip" popularized by hip hop culture from the San FranciscoBay Area.
Executive from big pharma: "How can we present the data from our new drug study in a credible, impartial light?"
Ghostwriter: "I'll ghostwrite the 'script, negotiate with a highly regarded physician for authorship, and submit it to the New England Journal of Medicine."
When you sit on your hand until it goes numb, then you proceed to masturbate so it feels like you are being jerked off by a ghost, or invisible spectral force.
"Man, I was getting so bored of normal wanking I tried ghosturbating... it felt great!"