shadow fucker = fucking the the shadows

that is, to part-take in sexual activity (of any kind) undercover from your close friends and deliberately withhold information relating to sexual encounters from close friends, even when questioned directly. insisting on your innocence when clearly you have been fucking in the shadows makes you a master shadow fucker.

to further expand:

This young bull and an older bull were grazing in a paddock. Beside them in the next pen there were hundreds of beautiful, blue eyed cows. The young bull turned to the old bull and said “Boy! Look over there!” He pointed with his hoof. “ Look at all of those beautiful, blue eyed cows grazing in that field over there! Look at them all!!!” he yelled with excitement. “C’mon! Let’s run over there, jump the gate, and have one of those cows!” There was a little pause, then the old bull lifts his head, smiles and turns to the young bull and advises, "Let us walk down quietly, young man, and not just service a few but the whole fuckin' herd!"

- The old bull is clearly a master shadow fucker

Q: why has the shadow fucker evolved?

A: many reasons; primarily due to the inability of women to keep their mouth shut.

A phrase to describe someone who is cognitively degenerating. Synonym of "going off the deep end". Can have varying degrees of severity.

Reference to the song "Hey You" by Pink Floyd. The line "and the worms ate into his brain" makes no sense in an otherwise linear and literal narration throughout the lyrics.