Based on the context and the answer, generate a question. 

Context: When Derek joined her , the door man unhooked the rope to let them through , still watching Lucy with undisguised lust as they walked in . A look of utter confusion shown on Derek 's features as they were granted entrance into the club . He draped an arm over Lucy 's shoulders and they made their way through the crowds of people . " So how 'd you do that ?

Answer:

He did n't understand how they were able to get in so fast .



What may be the reason for Derek 's confusion ?