Joke’s on you, I don’t know either (any) meaning of this abbrevation!

CNC = consensual non-consent, basically roleplaying being forced into sex.

The other CNC is a machine for creating physical stuff using computer. Like a laser cutter or a 3D printer. No idea what the actual meaning of the abbreviation is.

Computer Numerical Control
Consensual Numerical Control?
Cock Numerical Cock
Cock non-control, it’s only for the advanced pervert
We’ll strap you to a giant linear actuator and pump you full of viagra.