Captcha Top 10 worst

According to Wikipedia, CAPTCHA is a computer test used to determine whether a user of a system is a person or a computer. The main idea of ​​the test: to offer the user a task that is easily solved by a person, but which is impossible (or extremely difficult) to teach how to solve a computer.
However, sometimes it is even difficult for a person to figure out what is shown in the picture, or to solve a problem.
So, a dozen of the worst:





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Source: johnmwillis.com + several found on the web

In the comments you can add your options.