Acronym for "Too Stupid to Live".
Usually refers to a fictional heroine in a romance novel, but it can be applied to any fictional female character in a novel or film, and to a real female.
A well-known romance author invented this term, during mid-1990s, on a mailing list called RRA-L Romance Readers Anonymous List
1) "Don't hang with Shelley. She's TSTL."
2) "I hate Gone With the Wind! Scarlett O'Hara is TSTL."