He became drunk and lay naked inside his tent - Genesis 9:21
Noah, despite being the only righteous man, failed to keep his guard up - Genesis 6:9
After a glass of wine or so became drunk and passed out in his tent
Ham saw him naked and commited some unexplained sin - Genesis 9:22
Noah pronouned a curse on Ham's son that had repercussions for thousands of years
Noah let his guard down for only a moment but his sin led to dire consequences for his family