Masturcising is a form of exercise in which the person only masturbates instead of a more traditional form of exercise such as running.
"Alex put on his workout clothes and hit his bedroom for some masturcising."
The act of masturbating while on a piece of exercise equipment.
Instead of running on his treadmill, he likes to stand on it and jerkoff. He's totally into masturcising but he won't get fit or lose weight that way!