I have seen some interesting captchas over the years, and some of them intrigue me enough to find out why they are what they are - the history - the mythical meanings - all very interesting to me.

If you want to see all my other captcha research check out my master index http://bitbin.it/fbhOXm1W/

Here is another captcha word combo: the underground

Cooking, Food and Restaurants:
http://www.undergroundtapandgrill.com/

Definition and Pedia sites:
http://www.merriam-webster.com/dictionary/underground

Entertainment, Movies, and Music:
http://theug.com/
http://www.imdb.com/title/tt0772131/
http://www.youtube.com/watch?v=2x-4BAqk4wc
http://www.tv.com/shows/the-underground/
http://www.imdb.com/title/tt0114787/

Environment & Weather:
https://www.wunderground.com/

Misc:
http://www.tfl.gov.uk/modes/tube/?cid=tube
https://underground.net/
http://www.undergroundtour.com/

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http://bitbin.it/fbhOXm1W/ Interesting Captchas master index - links to all my captcha pastes
http://bitbin.it/S4WFaJLS/ BitBin Throwback Index - interesting pastes I found here