Fake Antivirus Scareware Popup

A pop-up suddenly takes over your entire screen: flashing red warning text, a countdown ticking down from five minutes, a claim that five viruses were just found, and a phone number to call before it's "too late." It looks exactly like the kind of thing that's supposed to make you panic first and think second. Investigate each piece of the alert, the branding that doesn't quite match your real browser, the countdown, the number, the button promising to "remove threats" before deciding what to actually do with a screen designed to make deciding feel impossible. The real answer, as you'll discover, is quieter than anything the pop-up wants you to click.