a popcorn film , not a must-own , or even a must-see 
(ROOT (NP (NP (DT a) (NN popcorn) (NN film)) (, ,) (RB not) (NP (DT a) (VP (NN must) (HYPH -) (JJ own))) (, ,) (CC or) (RB even) (NP (DT a) (MD must) (HYPH -) (VB see))))
(ROOT (NP (NP (DT ) (NN ) (NN )) (, ) (RB ) (NP (DT ) (VP (NN ) (HYPH ) (JJ ))) (, ) (CC ) (RB ) (NP (DT ) (MD ) (HYPH ) (VB ))))