Over the last few weeks, this picture has been circulating on the Internet. According to RationalWiki, that sentence must be attributed to Alberto Brandolini, an Italian independent software development consultant [1]. I've checked with Alberto and, unless someone else claims paternity of this absolutely brilliant statement, it seems that he actually is the original author. Here is what seems to be the very first appearance of what must, from now on, be known as the Brandolini's law (or, as Alberto suggests, the Bullshit Asymmetry Principle):

To be sure, a number of people have made similar statements. Ironically, it seems that the "a lie can travel halfway around the world while the truth is still putting on its shoes" quote isn't from Mark Twain but a slightly modified version of Charles Spurgeon's "a lie will go round the world while truth is pulling its boots on" (1859) which, in turn, might be inspired by Jonathan Swift's "falsehood flies, and the truth comes limping after it" (1710). Always according to RationalWiki, the concept may also refer to the teoria della montagna di merda ("the Bullshit Mountain Theory") as postulated by Uriel Fanelli, another Italian.

Anyway, there are a number of reasons to credit Brandolini and, apart from the overwhelmingly elegant formulation, the fact it's not that much about the speed of dissemination of bullshit but rather about the inherent difficulty to refute bullshit. There are plenty of examples ranging from the "Friedman was Pinochet's mentor" story to the infamous "loi de 1973" in France [2].

So, from now on, I'll refer to the Brandolini's law (a.k.a. the Bullshit Asymmetry Principle) which states that:
"The amount of energy needed to refute bullshit is an order of magnitude bigger than to produce it."

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[1] It's actually Alberto on the picture. It was taken at XP2014 on May 30th, 2014.
[2] A conspiracy theory developed by far-right/left politicians in France over the last years. [...]