It's when you have your face buried in your girls pussy!
I had my tongue so far in her I was neck deep.
ayon kay neck deep ika-26 ng Marso, 2011
The word is used in the workplace to refer to too many tasks given with too little time to accomplish them.
Paperworks are neckdeep, I may not be able to finish it on time.
ayon kay hardpen ika-03 ng Oktubre, 2010