BKCMS is an
abbreviation for the slang "Baap Ko Chodna Mat Sikha". It is used in reference to when a novice tries to teach an expert something.
It literally translates to "don't teach
your father how to fuck", from English to Hindustani.
1. Virgin son: Dad,
you should ask mom to give you blowjobs
Dad: Baap ko chodna mat sikha #BKCMS
2. Person 1: Bro I aced my finals this week,
you should study with me.
Person 2, who has been consistently topping in every class since the first semester: Baap ko chodna mat sikha #BKCMS