The Jenna Marbles face is the face you make when you just don't want to talk to somebody. It freaks them out until they walk away. The key is not to laugh or smile, JUST STAND THERE until they leave. it's kind of a cross between a frown and really shocked.
Girl: That guy was super annoying so I Jenna Marbles faced him.
That stranger was dancing on me and he wouldn't go away so i Jenna Marbles faced him.