Nun

I look in the rear view mirror. There's a nun in the car behind me.
She's eating.

I spend the next 10 minutes in a traffic jam trying to see what she is devouring. Every time I look, she's chewing, glaring directly at my reflected eyes and I miss the food being passed into her wrinkled mouth.

It's difficult to stare directly into the eyes of a nun, especially one that's eating. My eyes instinctively flick away from hers and when I dare to return my gaze, the answer to my query has vanished again into the nun's gullet.

Eventually the traffic moves forward but suddenly comes to a halt, causing the nun to slam on her brakes and, caught off guard, the nun gives away the mystery by spitting it onto the dash board whilst coughing crumbs.

Its a Viennese whirl.

I win, Nun.