Because it's a heap of fun. This search-term led jape, which has become a huge Thursday meme, is just too enjoyable to pass up.
Some people are, today, actually sitting at the Open Mobile Summit in San Francisco listening to someone drone on about how cell phones are now a sense more important than smell to today's youth.
Anyone sitting in that conference who still has a pulse will surely already have heard of Google's "Do A Barrel Roll." I know this because someone from the conference sent me a text and said: "Do it."
Might I therefore merely pass on this suggestion, as by doing it you might just have the most mindlessly enjoyable four seconds of your day. And four seconds is not to be treated lightly in this digital age.
All you have to do is Google search "Do a barrel roll." That's it. Then sit back and focus.
Naturally, Twitter is already delightfully excited by these four seconds and is attempting to turn them into a conversation for the whole day.
As I write, it is the number 6 trending topic out here.
Some twitterers have muttered that this is Google trying to be Siri-like in a "look what our search engine can do!" kind of way.
Others are bathing in the joy of another delightful Google Easter Egg. I merely imagine that someone at Google was bored and thought: "Hey, this is four seconds of my life worth repeating."