nicked in the head 

someone who has lost the plot. mild case of insanity. does unexplainable things usually when intoxicated

dave: did you see what tom did last nite

joe: i no i cant believe he tried shagging a tin of beans

dave: hes nicked in the head man, he doesnt know what hes doing after a few beers

nicked in the head by yorkshire kiddo April 25, 2011

nicked in the noodle

A little bit crazy and unsure

"my grandma is a bit nicked in the noodle''

nicked in the noodle by msalmon May 14, 2019

shiniest nickel in the piggy bank

when a person is so unintelligent that they cannot comprehend even the most remedial concepts of education

Jerome did not understand what the scientific term for water, h2o was - he damn sure is not the shiniest nickel in the piggy bank.

shiniest nickel in the piggy bank by Samran53 December 22, 2020