Which two-word English phrase, when read forward, describes a door but becomes a command when reversed?

Wordplay fans know that some expressions reveal their clever side only when read in reverse.

An open door. Photo by Pixabay

Riddle:

I am two words.

Forward, I describe a door fully open, with nothing in the way.

Flip me around, and I become a simple command you might give to a baby.

What am I?

The simplicity of the trick is part of its charm, nothing changes except the order yet the meaning transforms completely.

>> Check out the answer here