The 'Pentagon Hexagon Octagon' meme is a popular four-panel image macro that uses basic geometry as a setup for a punchline about sudden disappearance. The first three panels display shapes with five, six, and eight sides respectively, while the final panel introduces a fourth 'gon' that sounds phonetically similar: 'YourMoneyIsGone' or simply 'Gone.' It first gained major traction on platforms like Twitter and Instagram around 2017, typically used to mock poor financial decisions, the high cost of living, or the sudden loss of something valuable. The template's versatility allows users to swap the final panel with anything that has 'disappeared,' from grades to social lives, making it a staple of internet self-deprecating humor.