Just send out 6 random numbers to every schmuck who signs up. Just occasionally, some of the numbers will win enough for the schmuck to write some glowing piece of puff which'll go right up on the web page as "proof".
Like it says "can".
Every other combination of 6 numbers "can" as well.
If you want to pay $19 for someone else to think of 6 numbers for you, then that's your problem.