- Taking steps backwards.

- Hiding your face in your hands.

- Shifting glances around the room.

- Wide eyes.

- Crossing your arms across yourself.

- Taking a defensive stance/pose.

- Stuttering.

- Scratching the back of your head.

- Shifting weight from side to side.

- Exaggerated hand motions (fanning self, vague, gestures, etc)

- Nervous quirks (playing with your hair, picking at skin/clothing, fumbling with fingers, etc)

- Turning head sideways to avoid staring straight ahead.

- Opening mouth but no words coming out.

If you have any others, feel free to list them in the comments below!