Upper Storey

Noun - The brain; one's ability to think, understand, and rationalize.

Origin:
The head or brain, as in He's not all there in the upper story. This expression transfers the literal sense of a higher floor in a multistory building to the top portion of the human body. Richard Bentley used it in A Dissertation on the Epistles of Phalaris (1699), where he compares a man with "brains ... in his head" to a man who has "furniture in his upper story."

1. There is something wrong with her upper storey!
2. Sorry for that man, My upper storey is not great right now.