Not so cool at all.

CoffeScript "end"

CoffeeScript:
end = ->
test = (x) ->
    console.log(x)
    end()

test2 = (x, y) ->
    x + y
    end()

JavaScript:
(function() {
  var end, test;
  end = function() {};
  test = function(x) {
    console.log(x);
    return end;
  };
}).call(this);

Problems:
1. Ugly,
2. You'd lose the "return last statement" feature of CoffeScript. end() returns undefined and that's a problem in test2.

Solution:
Add a noop keyword so CoffeScript code would be:
test2 = (x, y) ->
    x + y
end