GitHub also has dice captchas. I remember one day in class we were doing a group project and using GitHub to share our work, and a friend of mine had trouble t

GitHub also has dice captchas. I remember one day in class we were doing a group project and using GitHub to share our work, and a friend of mine had trouble to log into his GitHub account and got this captcha. A team of 4 people in the class went to help him pass the (if I remember correctly) 10 tries you needed to have correct in order to log in. And they still took about 10 minutes!