He forgot his keys again; he's really not the sharpest tool in the shed
She struggled with the basic math problem, not the sharpest tool in the shed, perhaps
When it comes to technology, he's not the sharpest tool in the shed
I tried to explain it to him three times, but he's not the sharpest tool in the shed
Don't expect him to figure out the complex strategy; he's not the sharpest tool in the shed
He accidentally deleted all the files; he's clearly not the sharpest tool in the shed
She thought the Earth was flat, which suggests she's not the sharpest tool in the shed
Asking him to lead the project might be a mistake, as he's not the sharpest tool in the shed
He kept trying to use a hammer on a screw; he's not the sharpest tool in the shed
I’ve heard her say some rather silly things, so I think she’s not the sharpest tool in the shed
He just doesn't get it, does he?
No, he's not the sharpest tool in the shed, is he?
Not at all. It's quite frustrating.
He's not the sharpest tool in the shed, bless his heart
He's not very quick-witted or intelligent
His understanding is somewhat limited