He doesn't have both oars in the water

Meaning

This implies someone is not thinking clearly or is perhaps a bit foolish. It suggests they are trying to steer a boat with only one oar, which leads to spinning in circles.

Playful, dismissive

Used in a sentence

• I would not ask Gary for financial advice, he does not have both oars in the water.
• The new intern tried to mail a package using a stamp from 1994, bless his heart, he does not have both oars in the water.
• Stop arguing with him about the moon landing, he clearly does not have both oars in the water.