Similar to face palm, bridge pinch is the act of pinching the bridge of your nose with your middle finger and thumb in exasperation.
Waiter: "Our special tonight is the grouper sandwich."
Girl: "What is in it?"
Waiter: "Lettuce, tomato, various seasonings.."
Girl: "No, I mean...what makes it a grouper? Do I have to share it?"
Waiter: *bridge pinch*