This is an entry for a so-called publicity still. It's (very likely or proven) just a picture form promotion reasons since there is no spanking scene in the movie itself (or it has been cut).
Well this is not the usual publicity stunt, but an Ad for the movie Tortilla Flat which is supposed to be better than the older movie Woman of the Year.
Which is demonstrated by two spankings drawn on the advert.
Richard Windsor believes the MF spanking is supposed to be actor John Garfield spanking Katherine Hepburn.
IMDB: https://www.imdb.com/title/tt0035460/