In the early days of meme, it was common practice for nonnies to derail a long, wanky thread with the most god-awful porn they could find (or write on the spur of the moment). Here's a list of notable examples:
This practice fell into general disuse after about the first year or so, so that this eye-destroying example from Christmas Eve 2013 was a rarity at the time. However, derailing porn began to make a comeback in early 2015: