Head full of stump water

Meaning

This refers to someone who is not particularly bright or is filled with nonsensical ideas. Stump water is essentially stagnant, muddy water found in a tree hollow, which is not exactly a high compliment for one's intellect.

Colorful, insulting

Used in a sentence

• He keeps trying to build a shed without a level, he has a head full of stump water.
• Don't listen to his conspiracy theories, the man has a head full of stump water.
• I tried to explain how interest rates work, but he has a head full of stump water.