A sound in one's ears or actually in the brainsometimes made by a disease called Tinnitus. Missed deadlines can make the same sound.
"I love deadlines. I love the whooshing sound they make as they fly by."
Douglas Adams, English novelist
Usually preceded by "you are the", a title of praise for someone who has done something extraordinary. Functions identically to a host of other congratulatory expressions, such as "you kick ass," "you're the Man," "You're a champ," etc.