How you get free coins in sum dog?

Well, there is not any official cheats for sumdog, but there is a few glitches. If you go to training and select 'adding' try and use 'add 1 to a number up to 20'. Then play 'alien invaders' because that gets you lots of coins. Soon you will find that you level up fast! Also choose play computer and choose destroyer. it will help you. Trust me.