WIth the disk you could send it sliding like halfway into the room though.

butthen its obvious that someone has pissed under the door. plus with the disc you can get the piss way into their room rather than just near their door with lines of piss showing it came from the door

But if you get the frozen piss disc and slide it way under their door.

They will randomly have a circular puddle of piss in their room with no lines of piss showing where it came from and it would be in the middle of the room and be confusing as fuck

Plus if you get spotted doing it, a yellow ice cube is a lot easier to explain than you laying down outside their door with your dick out and your pants round your ankles.