Lyric discussion by naiveSimon86 

Cover art for Gloomy lyrics by Creedence Clearwater Revival

Sounds to me like he's talking about heroin addiction. The lyrics and the sound effects in the song point to that without really coming out and saying it - except for the "shoot" comment. Maybe Fogerty heard Velvet Underground's "Heroin" and got inspired.

I don't think you're right. Creedence Clearwater Revival have never made "drug songs". The bluesy sound of this song is inspired by John Fogerty's fantasies about "The Grand Old Southland" (Louisiana), just like the whole "Creedence Clearwater Revival"-album, or also the song Born On The Bayou.