'More Cowbell' is easily one of the most recognisable 'SNL' sketches in modern memory, and certainly Will Ferrell's most memorable.

The infamous sketch follows the recording of Blue Oyster Cult's 1978 hit, 'Don't Fear The Reaper', with rock legend Bruce Dickinson helping out with production. Dickinson, played by Christopher Walken, needs one thing and one thing only - more cowbell.

It's hard to know precisely why it's so funny. Maybe it's Will Ferell smashing the f**k out of the cowbell, maybe it's Christopher Walken remaining utterly stone-faced, maybe it's Jimmy Fallon being unable to keep a straight face.

Who knows. All we know is that this is one of the finest moments in 'SNL' history, and it's now finally available on YouTube.

Take a look.