If you poke someone or something, you quickly push them with your finger or with a sharp object.

If you poke one thing into another, you push the first thing into the second thing.

If something pokes out of or through another thing, you can see part of it appearing from behind or underneath the other thing.

If you poke your head through an opening or if it pokes through an opening, you push it through, often so that you can see something more easily.