Teenage Mutant Ninja Turtles ( or TMNT ) are a group of fictional characters . There was also a trilogy of TMNT video games for the original Game Boy system made by Konami , consisting of : Teenage Mutant Ninja Turtles : Fall of the Foot Clan , Teenage Mutant Ninja Turtles II : Back from the Sewers , and Teenage Mutant Ninja Turtles III : Radical Rescue .