BENNY "POOKIE" ROBINSON IN NEW JACK CITY (1991)
Nino Brown (Wesley Snipes) and the Cash Money Brothers. Recruited by police officer Scotty Appleton (Ice-T), recovering crackhead Pookie (Chris Rock) goes undercover bagging up rocks for CMB, reporting back to the cops. Unfortunately, the hard keeps calling Pookie, and eventually he starts smoking again, which leads to him blowing his cover.
Punishment for snitching:
The CMB kills him on the spot, then straps a bomb to his body. Scotty manages to deactivate it before it obliterates Pookie, so at least there's that.