grownups should appreciate its whimsical humor 
(ROOT (S (NP (NNS grownups)) (VP (MD should) (VP (VB appreciate) (NP (PRP$ its) (JJ whimsical) (NN humor))))))
(ROOT (S (NP (NNS )) (VP (MD ) (VP (VB ) (NP (PRP$ ) (JJ ) (NN ))))))