Short Answer: Because he wanted to show off his dental skills! 🐴🦷
Explanation: This funny answer suggests that the horse decided to chew with his mouth open to impress everyone with his magnificent teeth. It adds a playful twist to the riddle by attributing a human behavior (showing off) to the horse. The horse's dental skills become a comical factor, highlighting the absurdity of the situation and bringing a lighthearted tone to the riddle. The emoji adds an extra touch of humor, imagining the horse proudly displaying his teeth while munching away.