The term 'Brother of Groucho' refers to the three Marx Brothers, Harpo, CHICO, and Zeppo. Harpo was the eldest brother and was known for his mute character and playing the harp. CHICO was the middle brother and was known for his Italian accent and piano playing. Zeppo was the youngest brother and was known for his comedic timing and acrobatic stunts. All three brothers were famous for their roles in the Marx Brothers films.