I poked my brother lol and i dont know what it does help! and yes i know what poking someone in real life is.
Pokes are just a fun addition to the forums. They really don't do much except give you a notification. You can make games out of it, such as "Poke wars". Is your question answered?
Many big social networks(not naming) have the "poke" action. In my opinion it's just there to 1.) Annoy people 2.) For fun 3.) IT'S COOL I suppose that's about it. It gives you a notification and tell you [PLAYER] poked you. Go ahead an poke them back!
Poke is a way to distract a player while you do something with him like griefing his island or something like that! jk, actually it's a useless button