Swim loves smoking weed in lungs its the same principle as the bucket smoking method. The bowl filled with weed would be placed on the top of the bottle and carefully lit as this is happening the see threw bag is being slowly pulled down,pulling in the smoke into the bottle, the slower the the bag is pulled the more the bottle will fill with smoke. The bowl is then removed once all the weed has been burnt, The user then sucks back on the bottle pulling all the bag up the inside the bottle. You can either chug it back in one go, be siting down when u do this as this will put some people down quite quickly providing the lung is packed with smoke that is the bottle can be supported by your legs while u heat the bowl with one hand and pull the bag with the other or u can get a friend to hold it for u, The main advantage with smoking weed like this is that it saves it as u get more wasted. Be warned u will most likely have a coughing fit but afterwards it wont matter much
Feel free to tell what this methoud is called in your area swim knows theres different names for them