gistfile1.js

var EventAttacher = Class.create({
		
	events: "click,focus".split(","),
	
	initialize: function(element, handler) {
		this.element = $(element);
		this.handler = handler;
		this.events.each(this._buildObservationMethod.bind(this));
	},
	
	_buildObservationMethod: function(base) {
		this[this._buildMethodName(base)] = function() {
			this.element.observe(base, this.handler);
			return this;
		}.bind(this);
	},
	
	_buildMethodName: function(base) {
		return "is" + base.capitalize() + "ed";
	}
	
});

Function.prototype.callWhen = function(element) {
	return new EventAttacher(element, this);
}

var f = function(e) {
	alert(e);
}.callWhen("button").isClicked().isFocused();