Frotteurism  is known as a paraphilia that consists of erotic arousal by rubbing one's pelvic area or any other part of the body on someone else's body without their consent. René Zubieta  describes such conduct as “rubbing other people's bodies lustfully” in public places.
In Mexican-spoken Spanish, this rubbing is known as arrimón, from the verb arrimar, which translates as putting something against or next to something, or in this case, someone.
In Mexico, arrimón is both bad taste and a criminal offence (sexual abuse) punishable according to the federal criminal code. But what happens when arrimón is carried out on someone who has agreed to it?
Enter the new public movement #ArrimonConsensuado , or Consensual Arrimón:
#ArrimonConsensuado es una comunidad creada y dedicada para consensuar arrimones en el metro de la Ciudad de México, Guadalajara y Monterrey a personas mayores de 18 años, regidos bajo una normativa estricta para garantizar la seguridad, integridad y discreción de quienes gustan de tener un viaje placentero (enfocado a las damas) con personas confiables, respetuosas y responsables porque…
“El acoso sexual es un delito, el #ArrimonConsensuado no”.
#ArrimonConsensuado is a community created and devoted to consensual arrimones on the Mexico City, Guadalajara and Monterrey subway services for people over 18-years-old, regulated by strict norms to grant the security, integrity and discretion of all those people who enjoy having a pleasant ride (especially ladies) with reliable, respectful and responsible people, because…
“Sexual harassment is a crime, consensual arrimon is not”.
The movement's Twitter account currently has over 16,000 followers. Many of the members of the initiative sport bracelets that identify them as arrimoneros or individuals willing to get some kind of consensual frotteurismo during their rides on public transportation.
— #ArrimonConsensuado (@arrimonCMetroOf) April 12, 2015 
But the arrimón “official” bracelet is not the only way that people who like a bit of bumping to break up the grind of their daily subway rides can set themselves aside from the masses.
According to Milenio :
Los fans de los arrimones aprenden a identificarse mutuamente dentro del vagón con una prenda que sirva de señal, normalmente un listón rojo en la muñera derecha indica disposición para el arrimón.
Those who enjoy arrimones learn to mutually identify themselves inside the Metro wagon with some item that can be used as a signal, normally a red ribbon tied to the right wrist, which indicates [positive] disposition towards an arrimón.
Opinions about the correctness of arrimón are mixed, however. Isa Esteinou tweeted:
A little sad the life of someone who longs for an arrimón on the Metro…
Edgar Rivera exclaimed:
Consented arimón !!! I don't know whether to laugh or cry when I see there are these kinds of movements.
The online edition of Chilango  magazine shared important statistics about sexual abuse on municipal transportation:
Desafortunadamente, como reveló una investigación realizada por la Universidad Nacional Autónoma de México (UNAM), siete de cada 10 delitos que se reportan en el Servicio de Transporte Colectivo son por abuso sexual .
Sin embargo, no todas las agresiones sexuales se denuncian, ‘la prisa, el temor, el pudor, el tiempo, la burocracia en los ministerios públicos, entre otras razones, muchas mujeres prefieren no denunciar las agresiones’.
Unfortunately, as revealed by a survey carried out by the National Autonomous University of Mexico (UNAM), seven out of every 10 reported crimes committed in Collective Transportation Service refer to sexual abuse .
Not every act of aggression, however, gets reported; ‘rush, fear, shyness, time, bureaucracy in public ministeries, among other reasons, make many women prefer not to report the aggressions.’
Avendaño Law Firm summarised:
DELITO DE ABUSO SEXUAL EN EL METRO: es doloso y nunca culposo,aunque es peligroso por la interpretación que se le dé. pic.twitter.com/kNcr7ctQzs 
— avendaño abogados (@bogados_DF) April 8, 2015 
THE CRIME OF SEXUAL ABUSE IN THE METRO: is intentional and never reckless, although it's dangerous due to how it's understood.
Due to high demand  for the subway and other public transportation in the Mexican capital, it is vital that rules of coexistence are clear so that undesired and non-consensual conduct is reported and punished.
Consensual and desired conduct on the other hand, should go on freely without disturbing other passengers, the group argues.