The “More Cowbell” sketch was written by Saturday Night Live writer Will Ferrell, who also starred in the skit as Gene Frenkle, the fictional cowbell player. The idea came from Ferrell’s observation that the original recording of Blue Öyster Cult’s “(Don’t Fear) The Reaper” does feature a cowbell, though it’s subtle. Ferrell, with his signature comedic instinct, thought it would be funny to exaggerate the cowbell’s role in the song to ridiculous extremes.

The inspiration for the sketch was partly drawn from how certain musical elements can become unintentionally funny when overemphasized. Ferrell reportedly got the idea while listening to the song and realizing how funny it would be to have someone so passionately devoted to the cowbell that it disrupts the whole recording process.

The casting of Christopher Walken was key to the sketch’s success. Walken’s serious, deadpan delivery perfectly contrasted with Ferrell’s manic energy.

Interestingly, Ferrell didn’t originally think the sketch would be such a hit. He thought it was a niche, quirky bit of comedy. But during the rehearsals, the chemistry between Walken and Ferrell—and Ferrell’s physical commitment to the role in a too-small shirt—proved that they had something special. Walken later said that after the sketch aired, fans still come up to him and ask for “more cowbell.”