"If Potter's being possessed..."
Harry stopped listening, his jaw hanging slack. Dropping the extendable ear he backed away to collapse on a, thankfully empty, bed. Concentrating on pushing out Voldemort, Harry felt his scar throb. He put his and to it instinctively. He felt something with in, grabbed it with his magic and pulled. Thick black gunge followed his hand in moving from his head. With a groan escaping his throat, the last of it was removed. He could feel it in his hand, trying to bind to something. Harry began to giggle as an idea hit him. He reached under the bed with his empty hand.
Finding his target Harry touched it to the gunge. With a flash of light, it was absorbed. Harry put the new horcrux on the floor, and used it the way it was intended, followed by his friends once he explained what he had done.
The bedpan full, Harry charmed it to be invisible, with a notice me not spell, and a modified bubblehead spell, that he discovered while making his own dungbombs. It kept the smell in a container. Safe from discovery, Harry attached the bedpan to the ceiling with a permanent sticking charm. No one but Harry would ever find it.
Three weeks later.
"Dirty, dirty, must get clean, must wash. Be clean again. Don't want to be dirty, must wash."
"The dark lord's gone mad, hasn't he father?"
"Yes Draco, I believe he has."
Six months later.
"Still dirty, must clean, clean, clean, be clean on the inside."
Magical Mess Remover should never be drunk. It is especially bad to drink it if your whole body is a necromantic construct, and therefore, technically, a magical mess.
Disembodied once more, Voldemort set of in search of cleanliness.