I have been reading about various captchas for the past few days, and today I actually went and tried hot captcha.
It asks you to identify the "3 hot people" from a selection of 9, either 9 women or 9 men. I took the test around 30-40 times, and I _correctly_ cleared the woman's captcha only 3 times, and the men's captcha exactly once. Seems like I make a really bad human, and not a v smart bot either. :)