1.) Acronym for "Never To Return." Used at summer camps and summer schools to identify trouble-makers who would not be invited back. (The letters informing the kids' parents of their NTR status were not mailed home until the session was over.)
2.) Also used for lovers who don't live up to their potential.
1.) "After burning down the mess hall, that damn Goldberg kid is an NTR!"
2.) Yeah, she's got nice ta-tas and all but she just laid there like a dead fish. She's an NTR, for sure.