Small amount of anything. Small amount of food, bowl, cigerette, ect. A person can be a shnibb as well. Predominatly used to decribe the roach of a cigerette and such. West Seattle term. Can also be used as a verb.
"can I have a drag of your cigerette?"
"I would let you, but all I have left is a shnibb."
"I don't want to finish this cigerette so I'm going to shnibb it."