An outfit consisting of a wife-beater (of any color, but usually a discolored white one) that is tucked into jeans. It is named as such bevause that's what people in New Jersey wear to bed, probably.
"Dude, I went to Walmart to buy a Bon Jovi CD and I saw 6 people wearing a New Jersey Nightgown.
Gabriel woke up at 4:00 A.M. Therefore he was late, because he still thought it wasnighttime. This is when nightmorning can confuse someone while they are sleeping.