20G is the dictionary definition of "being chill." (Via)
While the earth's population continues to grow, humans are forced to live in ever closer proximity to each other, pissing each other off in new and disgusting ways. The neighbor note is the most effective medium to alert your neighbors to the myriad ways in which their way of life is destroying yours. So if you're going to leave one yourself and want to make sure your neighbors pay heed, take a cue from these authors and unload on that piece of paper with both barrels.