You may have seen those sites where you have to verify your age, this sounds complex and futuristic, but in actual fact all the user has to do is enter the desired date of birth! Which of course is going to be easy even if they have to use the calculator to get the right year!
So in order to make sure that site visitor is of the correct age then something more inventive is required, such as this image! After all who other than someone who is the right age for the site, is going to know what that little black thing in the image is!
Source [Geeks are Sexy]