idea: how to get passwords from stupid people

1) you send them a webpage link like fun.com/fun/?user=someIdNumber
2) they visit the page and see a note "you have to sign up to view the funny picture" or something like that
3) it asks them for a username and a password
(it could also repeat one or two times "invalid pass, please select an other one")
4) they log in, see the funny picture
5) you visit fun.com/fun/?getPass=someIdNumber
it shows you the passwords the person has written
done.

is there any page like this? if no, for the love of god, make it happen!