look up any word, like eiffel tower:
 
1.
A condition commonly seen in young children caused by lack of sleep due to an overnight. Usually consists of irritability, whining, crying, fatigue, fighting with siblings and parents, and an overall baditude.
Sara: "Mom, what's wrong with Elliot?"
Mom: "He slept over at Sam's last night. Must be a case of overnitis!"
by Sara and Linda June 19, 2006