“Shitposting” is an Internet slang term describing a range of user misbehaviors and rhetoric on forums and message boards that are intended to derail a conversation off-topic, including thread jacking, circlejerking and non-commercial spamming. On 4chan, the byproduct of shitposting is referred to as cancer. There are many Facebook shitposting groups with different themes, such as Simpsons Shitposting, and Star Wars Sithposting ("Sithposting" being a clever worplay on "Shitposting").
The exact origin of the term “shitposting” is unknown, but the earliest-known instance was submitted to the Something Awful Forums on April 10th, 2007, when member OhSNAP!Tray used the expression when referring to worthless threads on the site’s BYOB forum.
On June 28th, 2007, Penny Arcade Forums member IHasABucket commented in a thread about various types of electronic dance music in which he criticized other members for “shitposting.”