Unfortunately, if a user has not added their real name along with their username on SnapChat, there is no way to identify someone's identity based off of their username in the application. If the user has added their real name in the application, it will appear after clicking on the gear symbol next to their username in the friends list.
The mobile application SnapChat allows users to send pictures or videos for very short intervals of time to friends who also have the application. After the picture has been viewed by the receiver, it cannot be seen again. Some users do not add their real name to SnapChat, and the real names of those users cannot be determined within the application.