|Someone is wrong on|
xkcd is a webcomic by former NASA roboticist Randall Munroe. It is one of the most popular webcomics today, and is an influential part of geek culture. The focus is on math, science, internet culture, and personal relationships from the perspective of an introverted geek--the same perspective shared by most of the target audience.
Although far from confrontational, xkcd has occasionally dealt with controversial topics, and is firmly and consistently pro-science. Figure 1, for instance, takes the attitude that although the scientific consensus on evolution and the age of the Earth is correct, there is no reason to be bothered by others' willful ignorance, so long as they are not in a position to make terrible laws based on that ignorance.
 xkcd and the Internet
Munroe has a talent for putting relatively simple ideas in amusing and memorable joke strips; as such, xkcd is often quoted, linked to, and/or embedded in a post when there's a discussion on the Internet pertaining to science, math, personal relationships, or the Internet itself. Examples include the very common use of Figure 2, using Wikipedia's "citation needed" tag, as a way of criticizing someone else's unsupported assertions; and our own Internet template, adorned with a quote from Figure 3.