1 definition by Skamando

To grab your phallus with one hand, while using your other hand to shake your other arm with the overall intention of causing extreme pleasure seemingly caused by another person. Is similar to the Dutch Rudder.
Bobby was horny and lonely late one Saturday night, and so took to "Jumbo Jack"ing himself off.
by Skamando March 10, 2009
Get the Jumbo Jack mug.