Different arrays of farts with distinct sounds released while in the toilet (or any place). For example, the ass releases a sifting sound while the poop rushes down into the toilet water. Now the people listening from outside - either someone curious or someone waiting - will recognize it as a toilet tune. Some freaks will even record the fart sound and put it on their ring tone. Some legal issues have been filed due to lacking permission for using the sound without consent.
Bust out some toilet tunes off the freestyle my homie.