When I was in high school, we lived in a house with 2 bathrooms: one for my mom and her husband, the other for the three of us kids. Bathroom use worked out fairly well, as BJ's school started a 1/2 hour after Chris' and mine, and I liked to sleep in. ("Liked"? Who am I kidding? I still like to sleep in.)
Chris would take a shower first in the morning. Yep, we're a family of morning-showers. He had the unpleasant habit of leaving his dirty underwear in the bathroom when he was done showering. Even after we asked him not to, he'd leave them on the bathroom floor. Every morning BJ and I would stumble into the bathroom to get ready for school, Chris' underwear greeted us.
We tried many tactics to get Chris to pick up his underwear. We complained to Mom. We picked them up and left them on his bed. We played soccer with them as the ball, in front of him and his friends. We used them as weapons of mass destruction.
Each morning, they were still there, waving at us with a fragrant, freshly worn underwear smell. Eventually I gave up. I stopped hounding Chris to pick up his dirty underwear, and started picking them up myself. And what a thankless job it was! A little sister cleaning up after her older brother! Oh, the shame!
Except that I didn't put them in his dirty clothes pile.
When he left his dirty underwear in the bathroom and I picked them up, I put them in a bag (plastic, tightly sealed) in the back of my closet. One by one those dirty underwear migrated from the Chris' butt, to the bathroom, to the dungeon of my closet.
I didn't think much of the underwear. I just picked them up and put them away. Eventually, there were no underwear on the bathroom floor in the morning. Ta dah! I had done my job and done it well. No more underwear on the bathroom floor! Joy!
Strangely, however, Chris didn't complain. Who wouldn't notice that you've gone from lots of underwear down to, say, 2 pair. But I didn't hear him say anything about them. 2 pair: the one he was wearing, and the one in the wash.
One day, a while after the morning brush with discarded underwear had stopped, I heard my mom complaining, "How can you have only 2 pair of underwear? I just bought you new ones two weeks ago! Where did they go?" Chris, "I don't know." as he started another load of laundry.
Ooops. Someone noticed.
I went into the back of my bedroom closet, pulled out the (now quite heavy) bag of dirty underwear and brought it out to the livingroom. And handed it to Chris. In front of my mom and BJ, both of who looked stunned. I explained why I did it. BJ smiled. Mom said nothing (though I suspect she was laughing inside at my cleverness). Chris was relieved to have underwear again.
He never left underwear on the bathroom floor again.