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:

• Highlander/Methos mpreg "teddy bear" fic
• Fox Mulder/Alex Krycek, with Krycek as a merman
• Harry/Draco coffee enema
• Harry buttseckses Snape, but it's a spiritual thing.
• “Flippus Buttus”
• ”Feel yourself ovulating? Ready for me to knock you up again?“ Jared asked dirtily, watching Jensen with fascination, imagining him even more full with his babies.
• Mobile Suit Gundam Wing interspecies mpreg
• Ganondorf and Link from Legend of Zelda

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:

• ”The closest yaoi was... Harry and Ron porking in their room! Luna and Hermione see this in real time and its real life porking!“
• What sex with Tyler Durden was like
• Patrick/Pete from Fall Out Boy have fun with an ear of corn
• http://fail-fandomanon.dreamwidth.org/122934.html?thread=631935798#cmt63193OEA eats out OAA