Masturbating when you have a ****** requires a certain amount of play with your legs and spreading them a bit. Now imagine your hips are surrounded by a thick fiberglass shell that keeps them from moving. That way penetration is harder but the reward is incredible. The tease and denial sensation grows bigger by the second and when you finally see it coming and your legs want to squeeze one another you feel that what was preventing them from opening, now doesn't allow them to touch. The result is an explosion of dopamine that makes you want more and more restriction.