Doh comes from The Simpsons, the animated series created by Matt Groening that premiered in 1989, where Homer Simpson says it whenever he hurts himself or realises an error. Voiced by Dan Castellaneta, the line was inspired by an older Laurel and Hardy style grunt and became so widespread it was added to the Oxford English Dictionary in 2001. Clips of the sound spread early on soundboards and forums, and it remains a universal shorthand online for a stupid, self-inflicted mistake.