From Douglas Adams' _Hitchhiker's Guide to the Galaxy._ Phenomon in books andmovies where the populace at large completely ignores something strange and otherwise very noticeable, because it's only of concern to the main characters. Example: Fan1: There's a giant BAT flying above New York! Nobody noticed? Fan2: SEP Field.
S.E.P. FIELD
Meaning of S.E.P. FIELD in English
Slang English vocab. Английский сленговый словарь. 2012