Stop Online Predators Act - Amends the federal criminal code to prohibit using the mail or any facility or means of interstate or foreign commerce, or acting within the special maritime or territorial jurisdiction of the United States, to knowingly coerce an individual to engage in prostitution or sexual activity for which any person can be charged with a criminal offense, if such individual has not yet attained age 18 (current law) or has been represented to the person as being under age 18.