A person who makes idiot comments, decisions, and actions. This person can also be seen wearing ridiculous things. Also, if a person does not fit in, they are a lou. The word lou can be used as a noun, or to describe something or someone. If someone is a lou, they often times don't realize it until they are called one directly. As a friend, you should always let your friends know if they are being lous. If there is a lou in the area, call a "lou alert" by notifying others around you. This will keep you safe from further lou actions.
Person 1- "How many hotdogs did she eat last night when she was drunk?"
Person 2-"At least 15. She was being a complete lou"
Person 1-"Why don't you like him?"
Person 2-"He had a lou eye. Didn't notice til the morning"