friend of Bill W.

Etymology
An allusion to (1895–1971), known as “Bill W.”, one of the founders of Alcoholics Anonymous.

Noun

 * 1)  A recovering alcoholic, especially one who is a member of the organization Alcoholics Anonymous.

Usage notes

 * Because of the stigma attached to alcoholism, and Alcoholics Anonymous' commitment to protecting the identities of its members, the phrase is a furtive shibboleth for individuals to identify themselves as members of Alcoholics Anonymous, or to identify Alcoholics Anonymous meetings on schedules, etc.
 * Often used in eulogies and obituaries when the deceased person was a recovering alcoholic.