Phantom masturbation as you see a lot of people use nowadays. The participant acts as if they are masturbating and sometimes concludes with a fake ejaculation. It is usually used as sarcasm or a way to show displeasure. The word is a play on the boxing technique of shadowboxing.
Tom: Rick, you look like a transvestite.
Rick: *acts as if he is masturbating*
Tom: Quit shadowbating.
Rick: *acts as if he is masturbating*
Tom: Quit shadowbating.
by Mollywood34 April 25, 2012