The line comes from 'Fire,' the 1968 debut single by The Crazy World of Arthur Brown, where the singer declares himself the God of Hell-Fire over a pounding organ groove. The song topped the UK charts and became a psychedelic-era classic, and Brown's flaming-head performances made the lyric iconic. Decades later the scream resurfaced on soundboards and in memes, where its camp grandiosity fits any over-the-top entrance. It endures because few sounds announce chaos this efficiently.