Must-be meaning "Must Be Nice" derived from B.C. days dating 2008 to 2010.

Sources confirm that the expression came from Jeffrey Johnston's work ethic.

Applicable when:

ISRs come in late,
ISRs leave early,
ISRs take time off,
ISRs take a 2-hour lunch,
ISRs get a commission check,
ISRs take 2 lunches for the day,
ISR sales-kick offs,
If you are Jeff Johnston, Zadies for the ladies or Joe Lando

Working at a steakhoue
if you have Bill Ng's job or tattoo