I want to know if there is a site, or a possibility I can start this code, simple by sending friends a URL they can click on. For completely innocent purposes, of course.
The confirm dialog is intended for debugging purposes only. In Opera it always displays a checkbox for turning off JavaScript for the current page and in Internet Explorer it displays a checkbox from the second time a dialog is displayed by the page allowing you to bypass all further dialog boxes.
If you want to display a dialog that is not for debugging purposes then you should create your own using a lightbox script.