I wonder if "the latest thing" was a new expression back in 1922 when F. Scott Fitzgerald started writing "The Great Gatsby." Was "the latest thing" the latest thing, that is, new slang? If so, it's even funnier to see it used sarcastically like this. What a crazy trend it would be — a fashionable sex kink?
But then maybe there actually is such a trend these days. The "cuckold fetish" is a routine subject in Dan Savage's sex advice column, e.g., "Fuck My Wife, Please!"
Anyway, the sarcasm in today's "Gatsby" sentence is sublime. There's "the latest thing" and "sit back and let" and the marvelous "Mr. Nobody from Nowhere" — all of which only become funny — painfully funny — when you get to the tragically pedestrian phrase "make love to your wife."
It's also amusing that the problem is less that somebody is fucking his wife than that a nobody is fucking his wife. Mr. Nobody from Nowhere, who — if you violated the rules of the Gatsby project and go beyond the sentence — is the (supposedly) great Mr. Gatsby.
IN THE COMMENTS: Bill Harshaw uses The Great Google to show that "the latest thing" was, in fact, a well-established expression. The casual use of the word "thing" seems like modern slang. There are a lot of common phrases like "the thing to do," "a [fill in the blank] thing," "it's my thing," and "the real thing" that seem like things people would have said 100 years ago.
ALSO IN THE COMMENTS: Much discussion about how far Mr. Nobody really got: What did "make love" mean in the 1920s?