Arthur Luck—if anything can go wrong, it will, and at the most inopportune time
Arthur Luck appears to be a genetically heritable characteristic and can vary in its manifestation and extremity. Unlike most afflictions, Arthur Luck is utterly predictable. Arthur Luck WILL happen. The only questions are when, where, and how.
I remember when my parents left one of my brothers on the front porch when they went to church. Three hours later, he was still there, locked out and upset that his family had deserted him. Or, when my family came to see me off before a trip to Thailand, and my sister spent the whole time at the airport puking into a trash can.