to grab your urethra and peel your penis inside out to expose your urethra to fresh air, and then masturbate. a common masturbation technique used by primitive men who were not able to experience the use of a fleshlight.
Sally: Do you want me to jerk you off.
Fred: No, I'd rather you just shapleh me.
Sally: What's that?
Fred: It's when you flip my urethra inside out and jerk me off.