Pipes - Shotgun carb?

[Taken]

Swim just got a really cool liquid pipe that has a "shotgun carp"... The carb is at the very end and if he breaths through the mouth piece kinda slow no air goes out the bowl so he was wondering if its so you can take a hit and then blow the smoke back through while some one on the other end sucks and gets some smoke from the bowl too. This would be really cool to do with a girl so swim just wanted to make sure that's what its for so he doesn't go embarrass himself. Hares a pic (sorry for the kinda big size)