Use code ANGRY-BIRDS to get free power-ups in various angry birds games. Click on keyboard icon in options menu or in shop for angry birds friends.
More info in descriptions on Google Play Store angry birds pages.
I downloaded all my apps from Google play store on android.
I don't know if everyone will get exactly the same power ups but here is what I got:
ANGRY BIRDS ~ 80 SLING SCOPE LASER POWER-UPS worth £2.99
SEASONS ~ X80 COMBO PACK = 20 OF EACH BOOSTER worth £2.99
RIO ~ 20 OF EACH BOOSTER worth £3.81
EPIC ~ 100 LUCKY GOLD COINS , no exact price probably worth about £4
TRANSFORMERS ~ 150 GEMS worth £2.99 (need to complete tutorial before claiming)
FRIENDS ~ 10 OF EACH POWER-UP, no exact bundle price probably worth over £3 (need to complete tutorial and start weekly tournament before claiming)
There is no mention of this on other angry birds games, I tried entering it on other games such as go and star wars and it didn't work.