Derp is an expression associated with stupidity, much like the earlier forms of “duh” and “dur.” In image macros, the subject is typically portrayed with eyes that are pointed to each side. “Derp” is often used in rage comics to replace nondescript names or parts of conversation.
The first known instance of the word “derp” comes from the 1998 film Baseketball by South Park creators Trey Parker and Matt Stone. During a scene where they are caught smelling underwear taken from a woman’s private drawer, Matt runs out of the room and says “Derp.”
The 34th episode of South Park titled “The Succubus” aired on April 21st, 1999, featuring a character named Mr. Derp who briefly served as the chef’s replacement. In this episode the character performs various slapstick clichés like striking himself on the head with a hammer while exclaiming “Derp!”. South Park has included use of the word “derp” in other episodes as well, including a spoof of Rob Schneider.