Abbreviation of 'Jack the Ripper'. Used to describe someone who is deemed to be psychotic and/or murderous.
Guy 1: You seen that guy down the park who carries a knife with him?
Guy 2: Yeh, he threatened to kill me because I accidently kicked a football at him. He's a real JTR...
Guy 2: Yeh, he threatened to kill me because I accidently kicked a football at him. He's a real JTR...
by Joey Moto February 5, 2009