Certified Drug Free and/or Certified Drama Free. Most often seen on an iced out pendant with a UFO denoting the heights you can accurately achieve are limitless when you reject drugs or drama.
See that dude with the CDF pendant? He is certified drug free, he is a great guy to kick it with
ATF's CDF is a faction in the After The Flash games. In the newest game they are helping some commies called PRT who has taken over south USA cause they got brazils help!
Here comes ATF's CDF!
Oh no the PRT Commies got some help from CDF!