Everytime you use it you get a platinum coin (piggy bank plays yellow musical notes), but be careful it can turno into a broken piggy bank (while it sparks), even on the first try, at the same time it will give a gold coin. A rumour spread across Dolera, saying the slower you use the piggy bank, the more money you get total. This has been proven wrong. The money you will get total is determined when you earn the piggy bank. Also received as a present from Santa Claus and out of a Surprise Bag. The amount that you can get varies from 1 to 6001 gps (probably more). Christmas Event 2009 was a lucky Christmas for Tanaf who received 6001 gps from a piggy bank. The average amount obtained is around 400 gps (average from 100 piggy banks). Around 25% of them broke in the first try.
Reward from the Arena, Greenhorn level.
After breaking 50 Piggy Banks you will receive the Allowance Collector Achievement.