"Slippery Slope" is an exclusive meme from 4chan that started in it's /a/ section referring to people who start buying figures, manga, DVDs, Blurays, video games, and other such memorabilia of their favorite anime series and characters, manga series and characters, or video game series and characters. It mainly refers to a warning given to newcomers to buying such materials that once you start buying you may not be able to stop and you'll find yourself buying more and more, and more expensive items as time goes on, thus leading you to some financial troubles. It more than likely refers to the shape of a financial chart when a company's profits crash and goes into the red making a "slope" shape as the arrow goes down.

It's unknown who or when exactly the meme started, but most agree that it probably started shortly after "buyfagging" became popular again shortly after /a/'s 2010 Secret S/a/nta in which people rediscovered the joys of buying such materials and items again. Before that, when people would say that they had bought something from their favorite series (a figure or DVDs or the like) they'd receive a response of "What is this 'buy?'" This referred to the poor financial troubles that the anime industry went through from 2005-2011. The term didn't get really popular until 2011 after the meme "I warned you about those stairs bro" was coined. The obvious similarities of the two memes only helped further the popularity of the "Slippery Slope" meme and it can now be found constantly on /a/.

The meme has also spread to a few other sections of 4chan including /v/, /toy/, /b/, /o/, /co/, /fa/, /g/ and /vg/.