[Darnell]

pawn Code:

for(new i = 0; i < MAX_PLAYERS; i++)
{
    if(IsPlayerConnected(i))
    {
        new string[100], name[24];
        GetPlayerName(playerid,name,24);
        format(string,sizeof(string),"%s has slapped everyone",name);
        SendClientMessageToAll(-1, string);
    }
}

Not sure it'll work..I'm not that good of a scripter after all .
EDIT: Forgot a bracket after IsPlayerConnected.