An inverted Ffnord. The ffnord is used vertically with the bowl screwed onto the bottle's thread. The dronff is used horizontally with the toker sucking air (and smoke) from the top of the bottle, and the bowl is (normally crudely) inserted into the burned hole near the end of the bottle.
"Nah don't make a ffnordlid, have a dronff they're way easier to light".
A 2-litre soft drink bottle converted to be used for smoking narcotics. The bowl is screwed onto the top of the bottle and a hole is burned in the side using a floyn, or lighter. The toker sucks air (and smoke) through the hole while a floyn is held on the bowl at the top. Ffnords are notoriously difficult to light without a second person present, which led to the development of the Dronff.
"Got a coke bottle lid? I'm makin a ffnord", "someone light me ffnord for me"