var randomSound = integer(random(2)); // two random sounds
if(randomSound == 0){ 
     // play first sound here 
}
if(randomSound == 1){
     // play second sound here
}

if(randomSound == 2){
    // play something here
}

var num_songs = 2;
var sound_handle;

function switch_sound(snd)
{
     switch(snd)
     {
        CASE 0:
        sound_handle = snd_play(sound1, 100, 0);
        break;

        CASE 1:
        sound_handle = snd_play(sound2, 100, 0);
        break;

     }
}

void main()
{
   random_seed(0);
   var random_sound = integer(random(num_songs ));
   switch_sound(random_sound );
}