Refers to the number in which Chandler tunes his guitar. According to the introductory information of the "Friends" TV series, in the show, Chandler's commonly used tuning number 777 when playing guitar has special meaning to him. This number combination represents his unique personal musical taste, style or interest in music. Some kind of memorial that was important to him, this detail also became a characteristic of Chandler's character, giving the audience a deeper understanding of his personality and background.