Are out of their tree - Idioms by The Free Dictionary
be out of (one's) tree (redirected from are out of their tree)
be out of (one's) tree
slang To be crazy. After yet another sleepless night, I'm starting to feel like I'm out of my tree. He's out of his tree if he thinks this plan is going to work!
be out of your ˈtree (British English also be out of your ˈbox) (informal) crazy or strange; behaving in a crazy or stupid way, perhaps because of drugs or alcohol: She must be out of her tree, going swimming in this weather.