Laurel & Hardy was a British-American comedy film series (1927-1950) starring the British actor Stan Laurel (the thin one) and American actor Oliver Hardy (the obese one). They are one of the most iconic and popular comedy duos in the world. Laurel and Hardy have been referenced in The Simpsons numerous times.
Homer's famous line D'oh is a reference to actor James Finlayson in the Laurel & Hardy movies, who used to say the same line, but much slower and longer: "D'ooooooooh!". Since everything in animation has to go a lot quicker Homer said the line much quicker too.
References to Laurel and Hardy in The Simpsons
||Tracey Ullman shorts: Season 3
||In this episode Homer says D'oh for the first time, after being hit by a punching bag. The word was borrowed from actor James Finlayson in the Laurel & Hardy series, but at the suggestion of Matt Groening it was said much quicker to fit the animation timing.  .
||"There's No Disgrace Like Home"
||The scene where The Simpsons are giving each other electric shock therapy was inspired by Laurel & Hardy pie fights, according tot the DVD commentary.
||"The Wandering Juvie"
||Stan Laurel and Oliver Hardy are seen in prison uniforms, waiting in line to have their chains sawed through. This could either be a reference to their movie "The Second Hundred Years" or "Pardon Us", in which they indeed try to escape from prison.
||"Thursdays with Abie"
||In Granpa's flashback sequence several famous movie actors from the 1930s are seen descending from a train, among them Laurel & Hardy.
||"A Midsummer's Nice Dreams"
||Mr. Burns', being under the influence of marihuana smoke during a Cheech & Chong comedy routine, starts hallucinating and imagines he's watching Laurel & Hardy.
||Mr. Burns watches an old movie starring two comedians who resemble Laurel and Hardy and who are trying to move a piano. This is a reference to the Laurel & Hardy film "The Music Box".