SB (secret bae)
SB (acronym for Secret Bae) is a covert way to refer to a new romantic partner before it would be socially and/or legally acceptable to have a new romantic partner.
Mackenzie: Why do they call me Mackenzie SB (Secret Bae)?
Courtney: Girl, my divorce ain't final yet, gotta keep it on the down low.
Courtney: Girl, my divorce ain't final yet, gotta keep it on the down low.