[Jeffry]

Put this at your command.

pawn Код:

new gla;
gla=random(10); // Type here the number of messages you have.
switch(gla)
{
case 0: SendClientMessage(playerid, 0xFFFFFFFF, "This is the first message");
case 1: SendClientMessage(playerid, 0xFFFFFFFF, "This is the sencond message");
case 2: SendClientMessage(playerid, 0xFFFFFFFF, "This is the third message");
//....
}

I hope this helps you.
Just tell me if you need more help.