Musically:
To generate {using a suitable analogue instrument such as a bass guitar} an amplified pulsing bass note which may cause people to loose control of their rectum and shit themselves.

Fetish/Sex option 1:
To eat poo direct from a person's anus, more specificaly to induce gagging or vomiting by taking a turd into the throat direct from the anus of another person.

Fetish/Sex option 2:
For a man to go down on hands and knees and their partner to bend their penis back between their legs and perform oral sex from behind - then the man will defecate onto his penis and the face of his partner.