<human>:  Why was the silent film star Roscoe Arbuckle called the “Fatty Arbuckle”?
<bot>: Roscoe Arbuckle was a very fat man, and was called Fatty by his fellow actors in the 1920’s. He was a very successful silent film actor and comedian, and was known for his role in the silent film “The Butcher Boy”. He was known for his weight, and had a reputation for being very clumsy and accident prone.