His belt doesn’t go through all the loops
Dumber than a box of hair
All foam no beer
Smart as bait
The battery is not fully charged
Sharp as a bowling ball
Dumber than a bag of hammers
A few bricks short of a full load
A few beers short of a six-pack
The antenna doesn’t pick up all the channels
Chimney’s clogged
Doesn’t have all his dogs on one leash
Another brain would be lonely
Missing a few buttons on his remote control