An expression used by Keanu Reeves to express a wide variety of emotion:

• surprise
• approval
• dislike
• spare brain cycles

and many more! All through the actor's craft of subtle intonation and timing.

Typically uttered to a horse to get it to stop, but only in English-speaking countries. Tell this to a horse in Mexico, and the horse will interpret it as "Run down the mountain at a full gallop until you reach the lake."

So a four-year-old me had the misfortune to discover.

Also made famous by the character Joey on a tv show called Blossom and then later on some other crappy show.

The only reason I remember this is because one of my favorite Doom mods used a sample of him saying it for the sound the flaming skulls made when they zipped around. It was pretty damn funny to see a room of them zipping around saying Whoa.