Robert has an unusual sexual interest. He gets tremendous sexual satisfaction out of putting himself in crowded situations (elevators, subways, public buses) and rubbing his genitals against unsuspecting strangers. Robert might BEST be diagnosed as suffering from:

The correct answer is - Frotteuristic disorder.

Explanation:

Frotteurism or frotteuristic disorder is one of the sexually arousing disorders. It is characterized by touching or rubbing one's private parts or genitals up to the other person with or without their consent to get sexual satisfaction.

Robert's condition is similar to the frotteuristic disorder as he also gets satisfaction in rubbing his genitals against strangers and putting inside the crowded situations.

Thus, the correct answer is - frotteuristic disorder.