not have both oars in the water
lose one's mind
go potty
go ham
becraze
get one's freak on
crazen
dumb out
go mad
have bats in one's belfry
jimjam
take leave of one's senses
craziness
not right in the head
go bananas
meshuggener
apartments to let
go moggy
pop one's cork
wildin'
have a screw loose
bananapants
nutbar
flip
nerts
gobaloon
tapped
insane in the membrane
cuckoo
nutsy
loony tunes
drive someone crazy
madden
loco
cray-cray
buggish
half-cracked
nut job
off one's onion
off one's rocker
off the beam
wiggy
gone fishing
gaga
make
cuckoo for Cocoa Puffs
jiggy
hellify
crazypants
cray