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1.
LNB
LNB is an acronym for Late Night Book. Book is in reference of the social network, Facebook. Late night booking is not defined by any time constraints, but is usually accepted as activity such as posts done between the hours of 2-6am. Anything past 6am is considered "Early Morning Booking".
Aaron is up all night LNBing.

Did you see that wall post? Looks like someone's been LNBing.
by aznrapsta August 07, 2009
 
2.
LNB
Abbreviation for "Like nobody's business" which is a idiom meaning very well, very much or very quickly.
Used when doing something Like Nobody's Business.
Boys, I just downed that six pack LNB.
My mom can cook chocolate chip cookies LNB.
by JG-LNB September 12, 2010