However , BMO thinks that the two are possessed by a malevolent force and hides in the walls of Finn and Jake 's tree house .
Finn and Jake make a bet to see who can not talk the longest , and the two use signs to communicate .
BMO thinks that the two are possessed by a malevolent force and hides in the walls of Finn and Jake 's tree house .
Finn and Jake make a bet to see who can not talk the longest , and the two use signs to communicate .