negative bad luck.
mostly used as a comeback to be an asshole or something, also used to tell someone you dont want to do something.
or just throw it out there when ever cause you can! XD
John: hey, whats up?
Mum: can you take out the rubbish
Dylan Tarlintion: oi check this out
Evan Taylor: no
Dylan Tarlintion: do it or ill rape you
Evan Taylor: negbl
Leho Harrell: hows the wife?
Evan Taylor: NEGBL