In GTA IV, over by Faustin's house, there is a reference to a legendary musical note. If you are in the area, proceed to the dead end about a block away towards the water. Hop over the fence on your left while facing the water and a man should be sitting on a bench reading a book titled "The Brown Note". This is a note that when played causes bowel movements by the person playing the note. It's a joke for musicians :)