When you are tied up with some obligation that you don't want to be at and trying to leave. Often said when there is something else going on that you'd rather be doing at that time and want to get to as soon as possible.
Friend: "Hey, are you gonna meet up with us?"
You: "Yeah, I'm at this family dinner right now but gnawing at the rope. Be there as soon as I can."
A term used when a person is fucked up on Norcos (10mg/325mg), or "gnawing out" out when said person eats, snorts, or otherwise ingests the drug either illegally or way more than prescribed by their doctor.
Ryan: Yo, Steve-O, you look like you're feeling good.
Steve-O: Bahhhh, Burrr!
Ma: Man he's gnawing out on those norcos!
The eternally pleasurable act of providing someone you love (preferably a female, from a male perspective) with the utmost respect and pleasure to her her amazing reproductive organs.
I was gnawing on her pussy until all she wanted was me to hold her all night.