Over the past two decades, Charles Li, the owner and chief executive of Chicago-based fortune-cookie factory Winfar Foods Inc., has drawn on Chinese proverbs and popular sayings to write thousands of messages that go into the wafers. Mr. Li says he and his 80-year-old father-in-law spend long hours coming up with lines that are clever but still brief enough to fit on a ribbon of paper.

Winfar now supplies fortune cookies to more than 11,000 restaurants nationwide, and Mr. Li says he has had to bring in outside copywriters. “Writing fortunes is both fun and hard work,” he says, which itself sounds like something out of a fortune cookie.