Thousands of people around Melbourne were woken before sunrise today, by an unusual horn!
It was the sound of a ship horn emanating from the middle of Port Phillip Bay.
There's reports the horn was going off for more than 30 minutes, from just after 5am, and heard from Newport to Hampton.
Plenty of ticked off people also took their anger to Twitter:
Authorities say the sound was from an emergency horn, and it was a false alarm.