Was watching The Petrified Forest, a 1936 film starring Humphrey Bogart, and part of it takes place in a diner, and on the wall is a sign: Tipping is un-Am

Was watching The Petrified Forest, a 1936 film starring Humphrey Bogart, and part of it takes place in a diner, and on the wall is a sign: Tipping is un-American Keep your change So the idea was alive in some sense even into the 30s.