The best one I ever invented was a super soaker smoker.

It was a Super Soaker 100 pump action rifle and I put a bowl where the back bulb was and then you could pump it and shoot smoke into your mouth by putting the muzzle to your face. It was cool. Needed work though before I could market it as a viable smoking device. (see pic.)

I once made a bowl out of a cucumber that I hollowed out. Worked fine except for the weird taste and the occasional seed clogging it up.