This is used typically after somebody says a joke where they do not get a very big reaction. It is used in place of "no just kidding," but people generally condense the saying to noshk.
(Dan) That chick last night was all up on my nuts...
(Group) .....
(Dan) Noshk, but we did dance for a couple songs.
(Group) we knew you were lying, you never mac any chicks
a. Very nice tasting food or drink: 'The food was nomshus'
b. Compliment: 'You look nomshus!'
( Form the phrase 'To nom' as in to eat or chew. After 'nomming' the 'nommer' would show their reaction to the substance that had been 'nommed' by either stating that it wasn't nice or alternatively that it was very nice or "Nomshus"! )