Derp: A Thesis

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 and a caption that reads “DERP.” The words “herp” and “derp” are often used in rage comics to replace nondescript names or parts of conversation. (See also Are You a Wizard)
Origin
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.”