What is this, a bank day?

Posted by ESC on January 17, 2005

Today I was watching an old movie -- After the Thin Man . www.imdb.com/ title/tt0027260/ (One of the follow-ups to a wonderful series beginning with The Thin Man - 1934.) Detective Nick Charles opens an old trunk in a basement and a body rolls out. Nick says something like, "What is this, a bank day?" Later he talks about a man not being able to get money on a certain day because it was a "bank holiday."

My questions: what was a "bank day" and why was a body more likely to turn up then? Were people whooping it up and shooting each other on bank days?