sheer stupidity 

utter or unqualified stupidity

His post is sheer stupidity

sheer stupidity by sheer stupidity October 15, 2015

shear stupidity 

Getting an outrageously expensive haircut that ends up making you look like you got run over by a rusty lawnmower.

Did you see James? He looks like he just stuck his finger in a wall socket.

Yeah, splurging on a haircut like that was shear stupidity.

shear stupidity by backinbowl February 17, 2010