When something is very close fitting. Also can mean when someone is a cheapskate.
Also can be a play on words. Dick is a man's name and he wears a hat that is too tight....but it can also refer to the male genitalia and the foreskin around the head.
"Man, that dress she had on was tight as dick's hat band!"
"I will never date Johnny again. He is too cheap! Tight as dick's hat band."
Tight Nut Small Dick Syndrome or TNSD occurs when the penis and scrotum become very small and tight. TNSD makes an average size penis look like a tiny little acorn cock. TNSD is very common, and usually lasts for only a short period of time. Caffeine, cold weather and hard drugs often cause TNSD syndrome.
Friend 1: “Brah, my cock is so small right now, it looks like a tiny little acorn. It’s bugging me out!”
An old southern idiom. Could be used to identify a place that is empty, a person who is wound up, or any number of situations where the word "tight" is used. Nobody seems to know who Dick was. Apparently he had a tough time keeping his hat on his head.