A type of home-made bong.
Specifically a vessel, containing water, with a mouthpiece and a removable 'cartridge'.
The 'cartridge' consists of a metal or glass tube inserted into the vessel at an angle, below the water level.
Into this 'cartridge' is packed (and we do mean PackeD)first a slice of cigarette, then powdered or finely crumbled cannabis. The cartridge is then re-inserted to the vessel and the toker burns the draw and pulls on the mouthpiece until the cigarette burns through,it 'pops', the cartridge is emptied and he or she gets an entire lungfull of smoke.
Which the author must note, has a marked effect on the sobriety of the toker.
The shotties origin seems to be the West Country (notably Somerset and Devon)but it's use has been recorded as far afield as London and the North West of England.