tell (someone) what's what

To inform someone of the true facts or most fundamental information (about someone or something). After putting it off for a week, Sarah finally told Jane what's what and ended their relationship. You're so na?ve about the way you think this business operates, so allow me to finally tell you what's what.

Common Names:

Name	Pronounced	Usage
Ilma	EEL-mah	Finnish
Toby	['təubi]
BenjÁMin	-	Hungarian
Estera	-	Polish, Slovak, Lithuanian
Onyekachukwu	-	Western African, Igbo
AntÓN	an-TAWN	Galician