Necessity is the Mother of Invention...

Help! DS will not keep his hand out of his pants! Now, I know this is a normal "phase"... although if most of the men I know are any indication, it's not a "phase" that he will ever outgrow. And if that's not bad enough... he now feels it necessary to pull his diaper down and expose his "boy-parts". Not exactly appropriate for school and therapy.
So, the geek and I figured we would just dress him in one-piece pajamas for a while until he got over it. That worked for a few weeks. Except now he knows how to unzip them, so it's started again.
What to do? Well, for now we are blocking the zipper with a safety pin. It's working... but does anyone have any other suggestions? We can't really dress him in pajamas all summer!