Why is the ninth month called September?
"melodramatic radio serial" (later extended to television), 1939; so-called because sponsors often were soap manufacturers, from earlier horse opera "a Western" (1927). Shortened form soap for this first attested 1943.
: The average man and woman in this country live a soap-opera existencenoun phrase
[1939+; fr the fact that in radio days such shows were typically sponsored by soap manufacturers]