Based on the name and this situation, I assume a piss disk is when you pee into a shallow saucer, freeze it and then slide the frozen disk under a door so that it melts later and forms a pool of urine in someone's apartment.
Madness string 112329
There were all kinds of computers on the net. And they didn't all have compatible text modes. So you often got random garbled chunks of text if the other system used a different encoding or something. For some reason, the IRC servers that I found early on were I think in China, and even though most people were chatting in english, it was often garbled with weird symbols. And the long-distance BBSes that I used were always garbled. But we figured out how to understand each other well enough and had a lot of fun anyway.