Dumb And Dumber - There Is Nothing Funny About Death
When Harry and Lloyd are trying to revive the man choking on the peppers and lloyd tries to give him cpr, watch the waitress - she will cover her mouth to keep her from laughing.
True, the waitress does stifle a laugh a few times in the scene, but not when she covers her mouth. She smiles a little before she ever puts her hand to her face, but not during. Either way, it's a pretty big mistake- the director must not have cared enough to waste his time trying to get another take that was just as good.
How do you know she is covering her mouth from laughing? Have you ever seen anybody who saw something shocking to them?? They usually cover their mouth in shock.