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Niff is a street name for poppers.
also used for sniffs,
pass me the niff mate

ive only had 3 niffs
by agatha chris June 15, 2009
Nick and Jeff Warbler's (from Glee) fandom-made couple name.
Person on livestream: Do you ship Niff?
Nick: ...*huge smile*
by GeeUrie February 10, 2012
Everything and anything and everything inbetween!
I'm just a stupid niff!" "I will niff you." "Get the niff outta hurr." "Niff you n-n-niff you!" "Written in the niffs!" "Niffy niffs!" "Stroke a niff." "Rollin like a big niff.." "MLIN" (MY LIFE IS NIFF
by Nifferologist! May 30, 2011
boolean inverse of the function iff, equivalent to xor
same as nand or nor
0 niff 0 =0
1 niff 0 =1
0 niff 1 =1
1 niff 1 =0
by geek_1024 April 30, 2012
an abbreviation for niffler. its derived from the creature in harry potter which sniffs out gold, but it simply means "nothing" or "nevermind." see niffler
Dude 1: what's that your hiding under your bed, d3wd?
Dude 2: niff.
Dude 1: ok, if your sure.
Dude 2: just forget it, man.
by forearm October 17, 2005
Nigga I frequently fuck
Jenni: Isn't that yo boyfriend

Eva: NO! He's just a NIFF
by Eva Ehrat September 15, 2011
An English 50 pence piece. Hand in hand with biff
Mr D's sell large chips for a biff niff
by Will Satterthwaite May 30, 2005