Have you forgotten? "Careful With The Axe Eugene"
Pink Floyd deserve some kind of award for their career-spanning dedication to freaking people out, but of all their scary songs, ‘Ummagumma’'s positively petrifying "Careful With That Axe, Eugene" tops them all. Think a song needs frightening lyrics to terrify? Just turn off the lights and listen to this atmospheric masterpiece until it climaxes with Roger Waters’ blood-curdling screams.
Source:http://ultimateclassicrock.com/scary-rock-songs/