Maybe he was saving it to make a pipe?
It took me a while to figure out what was going on here. Evidently, Roommate #1 left an empty roll of toilet paper on top of the tank, which made Roommate #2 so angry that, instead of throwing the roll away himself, he grabbed a pen and paper and left a sarcastic note about a toilet paper roll having a place to live (the fucking trash can!). Then roommate #2 decided to answer that note with one of his own along with a solution to the problem in the form of a makeshift home for the empty roll.
I don't know what to make of these notes anymore. It's one thing to believe a guy would contort himself on a toilet bowl to deposit an empty roll on the tank instead of in the garbage, it's another to believe someone would take the time to write a note instead of just tossing it in the garbage. But I'm having trouble with the idea that Roommate #1, a guy too lazy to throw out an empty roll of toilet paper, is now not only leaving notes about it but building them tiny houses?