To engage in a type of laziness where only the most basic needs for survival are met, typically food, sleep, and sex. In humans, this behavior is most commonly observed on weekends, days off, and vacations. Named after the animalistic behavior exhibited by apes, monkeys, chimps, gorillas, orangutans, and wookiiees.
Dude 1: I just finished my last midterm and I have nothing to do for a week!
Dude 2: What are you gonna do with your vacation?
Dude 1: Order a pizza, invite a girl over, and go into Primate Mode for a few days.