Pull Faces Meaning

(idiomatic) To make abnormal facial expressions, especially for amusement.

Example: 1994, Stephen Fry, The Hippopotamus, chapter 2:
  So that they would be especially tired, David had spent an hour entertaining them in their cots earlier in the evening. He had drawn pictures for them with crayons and pulled faces, hummed tunes and danced stupidly around the room until it was time for the goodnight visit.