Clique em qualquer lugar.

<script type="text/javascript">
//<![CDATA[

var a = function(){
	alert("Funo A");
}
var b = function(){
	alert(this.name + this.message);
}
var c = function(){
	removeEvent(document, "click", a);
	removeEvent(document, "click", c);
	alert("Funo C removeu a funo A e C do onclick");
}
var params = {message: " com parmetros", name: "Funo B"};

addEvent(document, "click", b, params);
//removeEvent(document, "click", b, params);
addEvent(document, "click", c);
addEvent(document, "click", a);

//]]>
</script>