To be inebriated to the point where one loses control of their actions. Examples may include drunk dialing, no restraint over bodily functions, streaking, etc.
When out drinking with your buddies, the person who is the drunkest of the group or always engaging in drinking the most is "Steve Mckenna"... So when you are this person you are made an example to Steve Mckenna from Three Sheets, thus being called Steve Mckenna'd.