It's a prison slang. It's when someone passes off in formation to the authorities giving no names but in an informal way.
e.g. there is lots of drug dealing in here but I'm naming no names..
That's dry snitching. The cardinal sin especially in jail but still bad in any community.
If you need to "snich" or pass opinion on someone, grow a pair and name them. It's not a good look otherwise.
Morning AORers, what's happening?
If you see me jogging, kill whatever is chasing me