He is such a dolt.

He dolted around, making a fool of himself.

The dolts couldn't figure out how to open the door.

He dolted his way through the exam.

He is dolting around the house.

He made a doltish mistake by forgetting his keys.

He doltishly tripped over his own feet.

His doltishness was evident in his inability to understand simple instructions.

His dolthood was evident in his foolish actions.

His doltery was evident in his foolish actions.