A pipe used for smoking marijuana made from glass. Glass pieces tend to be larger than normal pipes and most often have a choke on either side of the bowl.
JJ:Dude, char you got your glasspiece?
Charlie:Fuk ya man were gonna get so fucked up tonite.
A tiny hole on the side of a glass piece used to get "a better hit" when smoking marijuana. Your finger is placed over the hole as you first start to inhale and then taken off while still inhaling causing more air to get into the pipe which in turn alows for a bigger hit.