If you want a classic, the Marx Brothers 'Duck Soup'.
Monty Python is always good .. I could watch the stoning scene or Biggus Dickus from the Life of Brian a dozen times over, and crack up each time. The Holy Grail is also great.
Jackie Chan is good, but I prefer his older stuff ... for pure laughs though, City Hunter.
Shaolin Soccer and Kung Fu Hustle are a lot of fun, with over the top wuxia silliness.