Minecraft wiki entry for Panda, associated text: Aggressive pandas have angry eyebrows and a tight frown.
Lazy pandas have a smiling face.
Weak pandas have teary eyes and snotty noses.
Worried pandas have 'puppy' eyes similar to tamed wolves.
Playful pandas have their tongues out.
Normal pandas have a frowning face.
Brown pandas have brown and white fur and a frowning face. This is the rarest variant.