Hello, in the movie "Head in the Clouds", Guy is going to a beano (a kind of party I guess) because Gilda invited him. Gilda is the girlfriend of Julian. While Guy is in the party, a girl is asking him - You are the troubled boy whose girlfriend Julian is planning to monster. Are you sad ? - I am thrilled for her (Guy replies) - You don't mind if she gets debauched ? ... I don't understand the part "whose girlfriend Julian is planning to monster", I didn't know that monster could be a verb, and I don't know who does what in this stuff Thank you for your help.