It’s kind of clever because not only do you have to read the ad but you also have to type part of it in so their catch phrase is more likely to stick.
It’s mostly throw up in your mouth, because it takes a while to even figure out that this is a CAPTCHA and because you know that you could be digitizing books instead.
Spotted on boxbe, although some light Googling suggests that this has been around for a few years.
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