A nap taken in the evening in anticipation of going out later, likely before a night of partying and excessive drinking. Often a result of tiredness from work or a lack of sleep caused by a previous night of partying.
Bro 1: Yo, what's good for tonight?
Bro 2: Dude, did you just wake up or something?
Bro 1: Relax, I was taking a party nap man.
Bro 2: Sick brah, lets get rowdy tonight!