Used to replace the multiplayer lobby theme.
But there is a deeper rabbit hole. Using tools like Wraith (Black Ops 2 Sound Studio) or T4M , modders extract the game's source sounds. When they re-pack custom MP3s (often hip-hop tracks) into the game's soundfile.all archive, the community began calling the output a "modded rap file." black ops 2 rap file
If you’ve downloaded Call of Duty: Black Ops 2 for PC (especially from scene releases or backup sources), you’ve probably seen a file with the .rap extension included in the crack folder. But what exactly is it, and what do you do with it? Used to replace the multiplayer lobby theme
: These files contain the decryption data required to "unlock" the .PKG (package) files you install. Without the correct .RAP file, the game or DLC will prompt you with a "missing license" error or fail to launch. When they re-pack custom MP3s (often hip-hop tracks)
Sources:
Ensure HEN is enabled. Plug the USB into the right-most port. When you launch the game, the system should automatically "reactivate" the content.