Random "What is" question

[Jinx]

What is the small inset plastic 'knob' in the back face of my passenger door just above the latch? It looks to have a slot in it as if to be turned with a screw driver. I've never noticed it until today when I was messing with the latch because of the infamous 1/4" window drop issue. 2019 Mustang. No picture right now, it's raining and the window is currently fully raised thank goodness.

 

[Ronin38]

Secret engine kill switch.

 

[Bullitt347]

It turns on and off the child safety door lock.
It is so the kid can't open the door from the inside if sitting in the passenger seat.
Door can still be opened from the outside if unlocked.

 

[Jinx]

It turns on and off the child safety door lock.
It is so the kid can't open the door from the inside if sitting in the passenger seat.
Door can still be opened from the outside if unlocked.

Thanks. Good to know. I've seen them on 4-doors before but never on a coupe. Gonna have to prank the wife with it. LoL