go nuts(Ты что, с дуба рухнул? Have you lost it?; стать странным, ненормальным; сойти с ума to start behaving in a strange way, to go mad (in Russian literally "to fall out of an oak tree"))
be out of someone's tree(When I mention this to McCartney, and remind him of exactly what was said, he starts laughing. "I love this guy," he says. "He's totally out of his tree." Lily Snape)
