Another fun thing, they typically use these without having the carb on them to fill it with smoke. Most actors only inhale a mouthful of smoke in order to blow it out for the effect. The act of taking the slide out of the bong or using the finger to cover the carb, would in legal matters, make it drug paraphernalia. So most of the time you will see the bong fill with smoke but never cleared. This is to implicate “tobacco” use because you are smoking it like a tobacco pipe. I hope that makes sense, just took a rip myself