Anal nutbag
From The Big Bang Theory Wiki
Howard refers to Sheldon this way when he's explaining his reluctance to spend three months with Sheldon in a small science station in the Arctic.
This expression may also refer to Freud's classification of the stages of human development. According to Howard, Sheldon has an anally retentive personality, with a compulsive seeking of order and tidiness, stubbornness and perfectionism.
