…slightly brighter than your average houseplant.
…not the broghtest bulb on the string.
And in the same vein, my friend Darren always says, “When I think that the molecules in his brain could have been used to make something useful, like maybe a couple hundred mosquitoes…”
A Baby Jesus short of a nativity.
A few spokes short of a wagon wheel.
The key’s in the ignition, but the car’s up on blocks.
A ball short of a trailer hitch.
A few decimal places short of pi.
A few peaches short of a cobbler.
A few beerstains short of a frat house.
A few puffs short of a bong hit.
The tornado’s touched ground, but there’s nary a mobile home in sight.
A few seeds short of a pumpkin.
A few chapters short of a book.
A few notes short of a song.
A few keys short of a ketboard.
A few keys short of a piano.
A few teeth short of a mouth.
A few buttons short of a waistcoat.
A few letters short of the alphabet.
A few words short of a book.
There’s a song called “I’m Going Slightly Mad” by Queen where he goes through some of these. Not all of them exactly suit your formula but the best one it.
In there you’ll find
You’re missing that one final screw
I’m one card short of a full deck
I’m not quite a shilling One wave short of a shipwreak (my fav)
I’m knitting with only one needle
I’m driving with only three wheels