Its from a Saturday Night Live skit with Will Farrell and Christopher Walken. The skit is "the rock band" Blue Oyster Cult recording in the studio their song, "Don't fear the Reaper" and the band member (Ferrell) with the cowbell is mucking the recording up by distracting the other band members. The producer (Walken) supports the whole cowbell thing to the chagrin of the other band members. Its pretty funny if you can find the original unedited un-f'd-with footage. There are a few YT vids with parts of the skit and a few others were YTubers have screwed it up "in celebration." It's not really funny unless you can see the whole skit. And the OP used the cowbell analogy wrong, but....anyway, I digress. LOL
eh, because I was bored:
From Wikipedia; (Don't Fear) The Reaper- "the song was memorialized in the April 2000 Saturday Night Live comedy sketch 'More cowbell". The six-minute sketch presents a fictionalized version of the recording of "(Don't Fear) The Reaper" on an episode of VH1's Behind the Music. Will Ferrell wrote the sketch and played Gene Frenkle, an overweight cowbell player. "Legendary" producer Bruce Dickinson, played by Christopher Walken, asked Frenkle to "really explore the studio space" and up the ante on his cowbell playing. The rest of the band are visibly annoyed by Frenkle, but Dickinson tells everyone, "I got a fever, and the only prescription--is more cowbell!" Buck Dharma thought the sketch was fantastic and said he never tired of it.[5]
It features the prominent use of a cowbell as percussion. The song was originally recorded without it and then overdubbed after the fact. Bassist Joe Bouchard remembered a producer requesting his brother, drummer Albert Bouchard, to play the cowbell on the track. "Albert thought he was crazy," his brother recalled. "But he put all this tape around a cowbell and played it. It really pulled the track together."[5] However, producer David Lucas claims that he was the one who suggested and played the cowbell.[6] Guitarist Eric Bloom remembers that he played it, but that the original idea came from David Lucas.[7]"
