To be honest, we don't know if the baby in this video is actually angry; he may just have some tummy trouble or be concentrating very intently on something that's out of the camera's range. Either way, this stubborn little guy just simply won't crack even the slightest hint of a grin! His caretakers even try to push his lips in the right direction--they literally attempt to turn his frown upside down--and it's all for naught; he just won't budge.
Check it out for yourself, and know that your stomach may hurt from laughter. We admire his determination!