Be careful what you ask a comedian. That’s my advice based on the advice you’ll find doled out in the new book from The Believer magazine. Contributors including Amy Sedaris, Zach Galifianakis and Louis C.K. answer a variety of questions. The most critical, in my opinion, was posed to author George Saunders: What book should I be reading on the subway?

I won’t ruin the whole joke, but I’ll tell you his response ends with the suggestion that you get a copy of, “Care to Make Love in That Gross Little Space Between Cars?” If you haven’t guessed, that’s the title The Believer stole for this book ($15, Vintage).

Hopefully no one will actually try to take you up on the proposition if you’ve got this book cracked open while riding the train. “It wouldn’t be hygienic,” notes Saunders, whose dirty little secret is that he lives in Syracuse, N.Y. — where there is no subway system. But he’s taken enough rides to know that you’re judged by the book in your hands, even if you’re not reading it.

“There’s some-thing sweetly public about reading a book on the train. It’s an advertisement for yourself, a window into your life,” he says. When you see books in other riders’ hands, you instantly know something about them.

“It’s a genuine way to connect with someone.” (And no, he doesn’t mean in that gross space between cars.)

With the rise of iPads, Kindles and Nooks, we’re losing the ability to spy on our fellow passengers’ reading habits. But, remarkably, we haven’t totally lost it. According to the Tab Farm, a website that tracks media consumption on the New York subway, 17 percent of riders still haul around paperbacks and hardcovers as commuter entertainment.

I don’t have hard numbers for Metro, but I suspect we’re similarly literary. I’ve tried to conduct informal surveys during my recent rides, but I keep getting freaked out by the titles I’ve seen. “Practical Aikido.” “I Don’t Want to Kill You.” “Unbreakable.”

Um, are these people trying to send me a message? Let’s hope no more so than I am with my copy of “Care to Make Love in That Gross Little Space Between Cars?”