Using the left hand in Indonesia is seen as taboo. It is because that is considered the hand that's used in the toilette. Sadly, for all you lefthanders out there, it is not appropriate to use the left hand for eating, serving food, or accepting things in Indonesia, although the stigma may be overrated given the fact that there are bound to be lefthanders within the society. A few more rules include pointing with your right thumb because doing so with your index finger is considered rude. Removing your shoes before entering a house is a courtesy.
Respect the culture and enjoy an unforgettable holiday!