Otak udang (shrimp brain) = Stupid If you ever peeled a shrimp that still has its head on, you know that the head is full of its crap.
Kambing hitam (black goat) = Scapegoat
Muka tembok (wall face) = Thick skinned
Cuci mulut (wash mouth) = Desert
Kaki tangan (leg arm) = Staff, assistants, minions
Indonesian is surprisingly literal compared to English. This is probably because most people have access to a second (ethnic) language to express euphemisms.