A Bosh is a home made modified gravity bong. Used more widely in southern states of the US, the Bosh is created from a bottle with holes in the bottom. Then a cap, with a bowl attached(using a socket from a tool set). You light the bowl and pull up, forcing smoke down and water out, then you hit it. This is a very good way for getting messed up.
"Whoa man, that dude just hit that bosh! IT was such a big hit."