Man on flight snarls like zombie

The latest viral video of an air traveler losing their temper—10m views and counting—doesn't show any acts of overt violence or criminality beyond disrupting a flight and disobeying the flight crew. But as in-flight horror goes, it doesn't get much more menacing than "man gnashing teeth and snarling alone in his chair like a zombie." The usual cautions about illness, drugs and other human frailties apply.