Starting August 26, 2010 Zynga launched Zynga Lotto. You get a lottery ticket with 9 squares. You can win 1 prize per ticket. You can choose 3 of the 9 squares. You get a prize if 1 of the squares contain one. You can ask friends for tickets (up to 20 a day). Each day you get a free bonus ticket.
The very first attempt (right after register) is very likely to have you win the prize. Upon the first scratch your odds are 1:9, on the second 1:8 and 1:7 on the third.
However seems like zynga algorithm generates a different random prize square every time you do a new scratch. So the win square can actually "move" 3 times.
There are 4 Sets of prizes: