Conversation so far:
Who were some of Coopers closer friends?
Cooper's twenty-year friendship with Ernest Hemingway.
What was important about his friendship with Hemingway?
The previous year, Hemingway drew upon Cooper's image when he created the character of Robert Jordan for the novel For Whom the Bell Tolls.
Which other friends did he have?
friends from the film industry, including directors Henry Hathaway, Howard Hawks, William Wellman, and Fred Zinnemann, and actors.
Who were his actor friends?
Joel McCrea, James Stewart, Barbara Stanwyck, and Robert Taylor.
Did he work with any of his friends?
CANNOTANSWER.
What sort of character did he have?
His friends and colleagues described him as charming, well-mannered, and thoughtful, with a lively boyish sense of humor.

Question: Can you tell me more about his sense of humor?
Self-contained rewrite: Can you tell me more about Gary Cooper's sense of humor?