(Kimihiro Hoshino/Getty Images; Alex Wong/Getty Images)

Even on Twitter, you have to be careful of the company you keep.

Amid the mystery of how a crotch shot made its way onto Rep. Anthony Weiner’s Twitter feed, eyebrows raised over another question: Why was the prominent New York Democrat “following” the college student the photo was targeted to — or any of the similarly young, unfamous women on his relatively short “follow” list?

It’s a teachable moment for VIPs diving into this newfangled social-media thing. As a rule of thumb, celebrities are followed by many times more people than they themselves follow, said Sree Sreenivasan, who teaches digital journalism at Columbia. The hitch is that “if you don’t follow a lot of folks, it raises the question of who are these people you are following. People will sift through your follow list and try to interpret all kinds of things.”

It’s all public, after all — something too many people lose sight of, said Zeynep Tufekci, a sociologist at the University of Maryland Baltimore County. What are the rules? “All you need is to bring the same common sense” to the Internet you would in real life. On Facebook, she refrains from “friending” her students “because normally I wouldn’t go to their parties either”; likewise, if the congressman was giving a speech, “he wouldn’t talk only to the young women.”

Weiner explained some of the logic behind his 198 followees to reporters on Tuesday: That he frequently asked his many followers (54K+ and counting) if they’d like him to follow them back. Perhaps it’s the young ladies with a crush who were quickest to respond?

“A fun account to look at is Shaq’s,” NYC-based technologist Michael Gruen (author of “Twitter for Dummies”) told us. “He follows a lot of women who are not famous but they’re attractive.” So it’s okay? Well, if you’re Shaq, he said. “It’s a public persona thing.”

Read also: The Fix: Anthony Weiner: I’m not answering any more questions, 6/2/11

Anthony Weiner’s plan to cool Twitter furor backfires, 6/1/11

Monica Hesse: Listen up, fellas: Naked man-parts? Not so sexy, 6/1/11,

Compost: Weinergate — Anthony Weiner’s Twitter image problem, 5/31/11