assigning a "user id" when touched script?

  
touch(integer total_number)
{
    key id = llDetectedKey(total_number - 1);
    llDialog( id, "Some random question?", [ "yes", "no" ], 21);  
     
    // blah blah
}

 tags. (Accessible through the # button above the message text.) There are a lot of... uh... I'm going to go with "purists" here who will be more inclined to help if they can read your code easily.

key gId;
integer gListener;//force of habit when playing with Dialog
integer gCom;

default
{
      touch_start(intege num)
      {
             gId = llDetectedKey(0);
             state Dialog;
      }
}

state Dialog
{
      state_entry()
      {
             //this is my standard dialog thingy
             gCom = (integer)(llFrand(2400000) + 1);
             gListener = llListen(gCom,"",Id,"");//will alow you to drop the listener

             //then all the dialog stuff here!
             llDialog(Id,"Foobar!",["Foo","Bar"],gCom);

       }
      state exit()
      {
             llListenRemove(gListener);//or llremovelisten... can remember
      }

}