I was going to have Ax explain a little more, but a shorter punchline is better for the joke. It gives you leeway to stop and crack up.
Jake: Marco, you seem jumpy
Marco: I can't sleep man, there's an Evil Monkey in my closet!
Jake: uh K, maybe you're just feeling weird after aquiring the gorilla
*Jake walks away concerned for his Friend
*Marco looks after Jake helpless, turns his head to look at his bedroom window
*A strange orangatang sized monky looks angrily at marco, then points a shivering finger towards him*
Marco: AAAAAAAAARRRRRRGGGG GGGGGHHHHHHHHHHH!