Crowdflower is dictionary based, meaning that almost every word, except for a few words which have been censored upfront, will be used as a keyword. Frotteurism is indeed a word that cannot be explained without mentioning age inappropriate words.
It is called frotteurism, from the French word 'frotteur', meaning 'to rub'. It is a recognised psychological disorder, listed in the DSM4 manual for clinicians. A psychologist who specialises in sexual issues should be able to treat it, or else refer the person to someone who can. A general practitioner (doctor) may also be able to provide a referral.
Weird is a very hard thing to define. What is weird to one set of people is normal to another and vice-versa. The real issue is whether or not the paraphilia is harmful to oneself or to others. Some paraphilias are both harmful and illegal; such as pedophilia (sexual interest in children), bestiality (sexual activity with animals [not illegal everywhere]) and frotteurism (non-consensual groping of strangers). Engaging in, or being aroused by, paraphilias such as these requires the intervention of mental health professionals and in some cases law enforcement. Other paraphilias whilst possibly strange to the majority of people are not illegal and not neccessarily harmful. Coprophilia (sexual desire from play with excrement [poo]) is a major example. Whilst it may be distasteful to the majority of people, it is really up to the individual whether or not they engage in consensual coprophiliac sex-play. Many paraphilias are not considered particularly weird either. An example might include katoptronophilia (sex play in front of mirrors). Once again it is up to you. The late Canadian Prime Minister Pierre Trudeau is often quoted with regard to what other adults do behind their closed doors; he said that "there is no place for the state in the bedrooms of the nation." This could be extended to also include that other people's opinions have no place in your bedroom. _________________________ This writer, having dealt with great numbers of people suffering from diseases that are transmitted fecally, such as hepatitis and a variety of parasitic diseases, has to disagree emphatically with the comment about coprophilia -- while still agreeing overall with the remarks in general.