Saw this posted on twitter the other day from @vudu_fans VUDU
You just buy the 4-pack of pudding at Wal-mart and submit the receipt via text or e-mail.
Receive a $4 VUDU credit code. "Limit" of 2 per account.
I just did this yesterday for ONE code, since I only bought 1. Got my reply with redemption code within an hour.
P.S. My local Wal-mart store had these priced at $1.38, YMMV. Will go back for more to get my "limit".