Create a kind of coupon with a entity references or node reference and no autocomplete I should create a webform with a field which is related to a node.
With webform seems no possible to add a node reference, so probably I should create a content type (coupon) instead of using the webform module.
Basically, when they complete the form they can fill the field "coupon" and if the coupon exists they can go through.

The most important thing is that the node reference should be a text field with NO AUTOCOMPLETE I don't want them to see the the other coupon. How do I create it?

I've already installed the module reference and entity reference and using drupal 7.12.

Thanks in advace
This is the way to avoid the autocomplete in a node reference
    unset($form['MYFIELD']['#autocomplete_path']);