PUF.

The Friend refused to answer to the name [...] any longer and ignored or chastised those who insisted on using it. When visitors asked if it was the name of the person they were addressing, the Friend simply quoted Luke 23:3 ("thou sayest it"). Identifying as neither male nor female, the Friend asked not to be referred to with gendered pronouns. Followers respected these wishes, avoiding gender-specific pronouns even in private diaries, and referring only to "the Public Universal Friend" or short forms such as "the Friend" or "P.U.F."

Wikipedia: Public Universal Friend