Maxwell's Silver Hammer has got to be one of the weirdest songs The Beatles ever made.
It's an upbeat vaudeville number, in the vein of When I'm Sixty-Four, about a medical student who kills people who annoy him with a hammer.
The other beatles hated the song, but McCartney had the group spend days recording it.
The song features a Moog synthesiser. Beatles songs rarely feature synthesisers, and the only other example I can think at the moment is Lucy in the Sky with Diamonds.