batty
cracky
up the wall
bananas
nut-bar
fruity
kee siao
toppy
siao
three stops short of Dagenham
daft
doolally tap
bonkers
bugfuck
berko
nuts
funny in the head
bats
gila
distraught
off one's dot
mad as a box of frogs
one fry short of a Happy Meal
crazy as a bedbug
meshugge
round the bend
flip
flip out
doolally
nutty
wud
round the twist
plumb crazy
madden
lunatic
off one's head
out of one's mind
becrazed
mad as a March hare
hatstand
bughouse
crackers
off one's chump
unglued
nutso
meshuggener
not right in the head
off one's trolley
cuckoo for Cocoa Puffs
reality challenged