Tested and working but abuse it asap before it gets patched. You don't get an obscene amount of coins however, just a couple of hundreds. Don't be greedy :p
Tools (download tools in the Tools section):
- Start Charles Web Debugging Proxy
- Go into Petville (click to play)
- Go into Bubble Pop Game and complete round 1.
Note: You must pop all 30 bubbles!
- You will see the following summary of round 1 game statistics
- In Charles (structure tab), look for the following line "http://fb-client-0.petville.zynga.com" or "http://fb-client-1.petville.zynga.com"
- Expand the line > expand "current/" > Expand "flashservices/" and you will see a few "gateway.php"
- Click on the "gateway.php", click on the "Request" tab on the top right window and search for the line "MinigameService.updateRound" (check from the last gateway.php upwards)
- After you have found the gateway.php with the functionName "MiniGameService.updateRound", right click it and select 'Edit'
- Click "AMF"
- You will see a 'sequence' and a 'params' Expand the 'params'
- Change the value of  in the params to the NEXT running digit. (example: 2 change to 3)
- Change the value of the sequence to the NEXT running digit (example: 11 change to 12)
Note: just +1 for whatever digit you have
- Click Execute when you are done.
- Now click back on the gateway.php with a pencil logo
- Repeat steps 11-13 to continue getting coins. Remember to always +1 the current value!
- Repeat till you are satisfied or probably when there is a error sync message. Just refresh and you will see your new coins.