A passing car filmed the pair as they drove through Santa Maria in Ecarnacon, Ecuador.
A woman can be seen lying on her back with her head on the handlebars as the topless man drives. Her legs are wrapped around the man.
The video has been shared widely on social media, and the couple are being condemned for dangerous driving.
Neither of the riders are wearing a helmet, and both have plenty of skin exposed.
Police are reportedly investigating the incident. The pair could face charges, and if the man is found to have been drinking, he could be looking at time in prison.