Creepy guy (or gal) in the movie theater.

[Hog1]

I have learned through many years of observation of deviant human behavior, the best way to handle such an occurance.
Casually lean over to "it" as if to say something, and hit "it" with a 2 second burst of about 40,000 volts off your hand held stun gun............stroll away to another location when appropriate