In The Great Gatsby, Jay Gatsby repeats the phrase "old sport" 42 times:
"Want to go with me, old sport?"
"I thought you knew, old sport."
"If you want anything, just ask for it, old sport."
The phrase is a paradox. It is a kind of boyish term of endearment and what an old-timer might call one of his cronies. As such, it combines both the "old" and new (sports), which sums up Gatsby's character: a mix of old (poor military man) and new (playboy mystery man).
Sports were becoming the hallmark of American life in the 1920s: we were becoming a nation that loved games. Tom plays polo and football. Jordan plays golf. Meyer Wolfsheim fixed the 1919 World Series. Sports was a new form of entertainment with an old criminal underbelly.
Nick also repeats the phrase "and so" over 20 times in the novel. His narrative voice in both inside and outside the story. "And so" has a detached ring to it, as if Nick doesn't want to advance the plot to its tragic end:
And so with the sunshine and the great bursts of leaves growing on the trees--just as things grow in fast movies--I had that familiar conviction that life was beginning over again with the summer. There was so much to read for one thing and so much fine health to be pulled down out of the young breath-giving air.
Other phrases too are repeated for effect. A number of characters (Daisy, Jordan, Owl Eyes, Gatsby) all say "Absolutely" to exaggerate and punctuate their feelings. It's one of those trendy words that Fitzgerald uses as part of the Jazz Age style of the novel.