cracky
up the wall
three stops short of Dagenham
toppy
nut-bar
kee siao
siao
fruity
bonkers
berko
bugfuck
batty
funny in the head
nuts
bats
daft
gila
distraught
off one's dot
bananas
mad as a box of frogs
crazy as a bedbug
one fry short of a Happy Meal
wud
round the twist
plumb crazy
not right in the head
meshuggener
flip
flip out
becrazed
meshugge
insane in the membrane
unglued
doolally tap
loony tunes
round the bend
off one's trolley
mad as a March hare
gone fishing
nutzoid
off one's onion
off one's rocker
nutty
off the beam
out of one's mind
off one's head
bughouse
hatstand
crackers