Carla will often times give a llama-style greeting to you, if your technique is good.
Approach from the front, keep your hands down (they don't like to be touched unless during feeding time), and lean in. She wants to smell your breath. Her mom, who we call Mama Llama, taught her to do this. Together they're a good team, greeting guests in the pasture. A very fun thing to do, and a good photo opp.