To pretend to be dead. To lie down in a manner in which someone would be presumed dead. Usually done with a group of friends for comical reasons or just out of plain boredom. In order to successfully Dead you must have a picture taken of the person Deading and the Dead must be named.
Dude 1: Yo why isn't Frank talking to me anymore. It's been 10 years.
Dude 2: Frank's been dead for 10 years. You killed him.
Dude 1: That explains why I'm in this jail cell.