Refers to Glass-On-Glass, or GonG. Standard
water pipes (bongs) use a glass
slide and a rubber stopper to seal off the chamber, but GonG is a more advanced system that involves precision laser glass cutting so the GonG pieces
fit perfectly together, creating a more efficient means of smoking. GonG is also a way to "add on" to your bong, including ashcatchers, filters, diffusers, pretty much anything that is compatible. The most common sizes for GonG accessories are
14.4mm and 18.8mm(referring to the width of the glass opening). Glass-on-Glass bongs
hit harder and smoother than conventional bongs.