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3. fsn
acrynom for Fat Slag Nan.

someone's nan who is fat, and was a slag in her youth.
Dave: Did you hear about Jonny's nan the other night?
Bill: Yeah, shes such a fsn!
1. FSN
acronym,
F.S.N stands for F*ck School N*gga
John: Too many homework dude!
Jim: Yeah FSN man!
2. Fsn
Former slave name. Used by African Americans particularly of the 1960s Black Power generation to describe the rejected names they were born with.
On May 2 1973, Black Panther activist Assata Shakur (fsn) JoAnne Chesimard, was pulled over by the New Jersey State Police, shot twice and then charged with murder of a police officer
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