Not Too BrightOne worth keeping
“You don't yoke a calf 'longside the ox.”
California outlawed child marriage while 32 states still allow it.
In the same vein
All Not Too Bright →Dense. All weight, no sharpness.
Looks alert. Isn't.
Not enough sense in there to do the smallest job.
Can't manage even the simplest task.
Not sharp at all.
He's lost whatever sense he had.