Type "do a barrel roll" into Google now. Go on. We'll wait.
Pretty cool, right? Last night it became a trending topic on Twitter. No one knows how long it's been there, but it references an internet meme that's years old, so the big G may have programmed it in a long time ago and left it waiting to be discovered. The merry pranksters.
If it doesn't work for you, try a different browser. (It initially brought up a blank screen in Safari for us, then worked in Chrome.) The browser should roll over clockwise, as if it's doing a barrel roll. You'll get the same effect if you type in "z or r twice." Why? Well, it's a reference to an old SNES game.
Those of us old enough to remember Star Fox on the Super NES will recall the phrase was uttered by Peppy Hare. You executed the move by pressing Z or R twice (hence the browser rolling when you enter that phrase into Google too), and if memory serves us correctly, it was used to deflect shots from enemies. But forgive us if that's wrong, a lot's happened since the game was released back in 1993.
A YouTube search throws up all sorts of remixes, but those in search of a retro fix (or just wondering what the hell we're going on about) can see the game in action here. Dig those polygon graphics.
Urban Dictionary lists the phrase as a witty retort when someone asks for important life advice.