J.R. Smith goes underground on game nights, preferring to ride the subway from his uptown apartment to Madison Square Garden. A handful of commuters recognize the extravagantly tattooed straphanger, but mostly Smith is ignored as the train rumbles toward Penn Station. “Most people find it hard to believe it’s me,” Smith says, “so they don’t say anything.” Smith, of course, is not your average working stiff. He is the only one on the train with the job description as a high-energy, highly unpredictable shooting guard for the New York Knicks. On the subway, however, everyone is equal and that makes the kid from New Jersey feel like a typical New Yorker. The one drawback — and it’s a minor one — to commuting on the subway is that Smith can’t get wireless reception. No phone calls, no text messages and mostly, no Twitter. A picture may be worth a thousand words, but J.R. Smith says plenty about himself in 140 characters. From openly flirting with gorgeous women to trading insults with critical fans to mocking himself for shooting an airball from the foul line, Smith and Twitter are a match made in social media heaven. No topic is off limits for Smith, who uses the Twitter handle @TheRealJRSmith, has 280,000 followers and could probably use a Parental Advisory label on his feed. Last season, the NBA fined Smith $25,000 for posting a Twitter photo of Tahiry, a reality television star, who appeared half-naked. Smith apologized for his error in judgment but the incident only increased Smith’s profile, especially among the female audience. “I’m a good-looking guy,” Smith says, smiling. “They’ve got to follow me.”