Code:

---

// Has 3 animation cycles
define ASceneMax, 3;
 
string AScene[ASceneMax];
...
ACTION RandomAnim
{
    AScene[0] = "Walk";
    AScene[1] = "Run";
    AScene[2] = "Stand";
    // ...
    while(1)
    {
        if (!my.skill10 & key_space)
        {
            my.skill11 = int(random(ASceneMax));
            //
            my.skill10 = min(my.skill10 + (my.skill1 * time), 100);
            ent_animate(my, AScene[my.skill11], my.skill10, 0);
            wait(1);
        }
        wait(1);
    }
}

---

This should work, but I'm not sure if you can use arrays with strings. If not, then I've got another example for you...