[LetsOWN[PL]]

Very simple to do.

First, let's make some worlds, what will be used for this "hand waving"

pawn Код:

new WaveTexts[][3] = { "Hello", "Hi", "Wazap" }; // [3] means, that there are 3 words only. You can add your own ones..

Now, lets make command, what will detect if player says that:

pawn Код:

public OnPlayerText(playerid, text[])
{
        for(new Order = 0; Order < sizeof(WaveTexts); Order++) // Will search if player (playerid) write one of WaveTexts's text
        {
            if(strfind(text, WaveTexts[Order], true) != -1)
            {
                ApplyPlayerAnimation(playerid, ...) 
                    ApplyPlayerAnimation(playerid, ...)// Sorry, but forget the code for wave animation. Hope you'll find it out for yourself :) PS. Duplicate this function, to be sure that it will works!
                return 1;
            }
        }
}

Wua-la.