My older brother lived and studied in Indonesia for 6 - 7 months. He was living in a share house in Lombok with 3 other people and was lucky enough that all of the Indonesians he was living with smoked a bit of marijuana which my brother was so thankful for as he loves his weed and is a down to earth surfie hippie........
Not so lucky for one of the young ladies that lived their though was the cops got word some how that a male occupant was in possession of marijuana and they found 0.4 grams of marijuana in the males occupants rooms, however he did not smoke weed and when tested the results were negative for having marijuana in his system... The weed belonged to a young lady that was living their, (aged 23 at the time), she owned up to it, they all tried bribing the lead detective or police officer with all the money they had which was a considerable amount, ($2,000 AUD), but he was one of the ones that wasn't corrupt and didn't take bribes so the lady got sentenced to 15 years in jail!!! Imagine that, 15 years jail for not even 1 joints worth of marijuana....
So be extremely careful while over their because the dealers will set you up and even though some of them may not and you find a legit dealer who's not going to dog you in, you might happen to be being watched by a Police Officer that is not corrupt and doesn't take bribes and that will lengthen your holiday dramatically in a small dirty Indonesian jail which is just how everybody wants to end their holiday! 8)
In saying that though, I was told that it is very rare that a Police Officer will not take a bribe to look the other way and forget what they just saw... A measly $50AUD will usually be sufficient enough for most things as that is apx a months salary to them.
If you enjoy shrooms though they do make a mean milkshake from some of the stalls if your lucky enough to find them and they will rock your world to another dimension, literally hahaha.
Anyways hope you enjoy your time over their and just be extremely careful with everything you do and try to steer clear of drugs all together because it's just not worth it!