https://gamefaqs.gamespot.com/a/forum/1/1298179b.jpg Found out a bit of info. The lab assistant who looks after the monkeys each day. She's putting lipstick on rabbits and stuff. Gets pally with the chimp. Every day, it's studying her movements more and more. He notices the number on the keypad, 247. Monkey says to himself that he'll remember that. Notices the lipstick and stuff still laying about.
While the lab assistant is messing about with the rabbits, monkey goes to the mirror, puts on the lipstick. Goes to the door, enters 247, walks out the door. Guard on the door just says "Alright, Kirsty?" and let's the monkey go off.