There are many ways to do this, probably the laziest way is to:

switch(irandom(5))
{
case 0:
    x=32;
    y=32;
    break;
case 1:
    ...

}

This requires you to manually enter the positions which you wish to jump to. It could be a pain if you want to add more positions. An easier way is to place a specific object in the room editor and jump randomly to one of those objects. And if you wish to jump to a random object (for example, if each of your six positions has an object sitting on it), then you can do something like:

var xpos,ypos,num,place;
num=0;

with(someObjectYouWishToJumpTo)
{
    xpos[num]=x;
    ypos[num]=y;
    num++;
}

if(num>0)
{
    place=irandom(num-1);
    x=xpos[place];
    y=ypos[place];
}

Which is probably better. A more Game Maker-specific version would probably go something like this:

if(instance_number(someObject)>0)
{
    target=instance_find(someObject,irandom(instance_number(someObject)-1));
    x=target.x;
    y=target.y;
}

I'm reasonably sure that this would work, and it's probably faster than the last code sample.

As always, I haven't actually tested the code I've posted, but you get the idea.