My return falses aren't working. Happen to know why?

Code JavaScript:
 
var drop_selected = document.getElementsByName('search_category');
	for (var x in drop_selected) {
		drop_selected[x].onclick = function(){
			or (var c=0; c<drop_selected.length; c++) { 
				drop_selected[c].setAttribute("class", ""); 
				return false;
			}
			this.setAttribute("class", "drop_selected");
			return false;
		}
	}