[nodata]

http://xkcd.com/810/

[eru]

http://xkcdexplained.com/post/1395792545/constructive

[archgoon]

Captchas are not restricted to reddit and social news site, despite what your link claims.

[eru]

Oh, that was just to make fun of xkcd. I don't think xkcd links are really that good an addition to a discussion here.