Gross Post Alert!

I know this is a gross post, but I'm looking for a real solution. If you don't want to read about poop, then stop here and move on.

Miles has a diaper fetish. Actually, it's not a diaper fetish, but a "what's inside the diaper" fetish. I thought I had the upper hand on the issue by making him wear a onesie because that blocks access to the diaper, but he's found a way around that obstacle. He can access his diaper by going up the onesie leg. TWICE today he has come to me proudly bearing gifts of "poo poo" in his hand. I'm not overreacting to it. We go and throw it in the potty then disinfect his hand and I tell him to leave the "poo poo" in his diaper, but he's not catching on. He's proud of what he is bringing me and it makes me want to throw up. Any suggestions?