A no-CD crack is a modified executable (.exe on Windows) file. It bypasses the CD checking mechanisms, allowing the user to play without inserting a CD. Commonly used on copied (pirated) games
You might also see the tags NO-CD before a name on Counter-Strike. This indicates the server is running the anti-cheat system, "Cheating-Death", but the user is not running it.
Cheating-Death has been discontinued, and is no longer supported (www.unitedadmins.com)
"Damn, I downloaded that new Hitman game, but it's asking for a CD"
"Hold on, let me send you a no-cd crack"
"OMG WHY DUZ MY NAME SAY NO-CD"
"Because you're not running Cheating-Death"
Mom: How Nice to meet you, Kelly!
Kelly: What you say?
Mom (under her breath): NOCD, (grunt sounds)
Middle and upper class British put-down saying to describe those perceived to be of lesser social standing. Most popular post World War II and the fifties but stll comprehensively used today by those of that generation.