When I need to post something, whether it's a credit card number or just a remark saying "First!" in a comments section, I often have to type in the letters or numbers of a Captcha. This is the wiggly word used to verify that a human, not a robot, is requesting to post something to a website. Some of them are drawings made to look like letters, some of them are words that couldn't be read when a company was digitizing a book using OCR (sending the word to a human to be read is quicker than getting an employee to thumb through the book and correct them). Whatever, I can't always read them, and luckily the bank/auction site/blogger with inflated sense of importance always gives you several tries to read them.
The idea is that an automated system can't read them., and so a botnet trying to use your credit card to buy uranium on the world market would not be able to do so. (Assuming uranium ore dealers use Captchas, of course.) Only a human being with cognitive skills can figure out what letters and numbers are in it. That makes them a type of Turing Test, and in fact the originators tend to claim that CAPTCHA stands for "Completely Automated Public Turing test to tell Computers and Humans Apart".
Anyway, that was a long introduction to say: Hey, I thought this was pretty funny.
From Weaselking via More Words Deeper Hole.