An unintentional over posed facial expression, expressed in the lips to look sexy while taking pictures, to give a fuller lip effect or more intriguing facial profile on camera. Characterized as the lower lip or general mouth region being over relaxed and droopy, giving the "syndrome mouth" appearance, which ultimately makes them look like a joke.
Director: Give me the "I know you want me" look.
Amateur model: *posing the syndrome lip instead*
Director: Your lips are over relaxed. Look more stern and regain your posture.
Amateur model: *continues to look like a goof*
Director: Gahh you're still giving me that syndrome mouth look!