Four minutes into a video that was posted on Instagram last month, Justin Bieber leaned into the camera and adjusted the front of his black knit beanie. For some of his 130 million followers, it was a signal.
In the video, someone had posted a comment asking Bieber to touch his hat if he had been a victim of a child-trafficking ring known as PizzaGate. Thousands of comments were flooding in, and there was no evidence that Bieber had seen that message. But the pop star’s innocuous gesture set off a flurry of online activity, which highlighted the resurgence of

)