You're talking about having ice in the bong when you hit it right? When I read the title of the thread the first thing that came to mind was a bong made of ice...but then I realized how impractical that would be.
ice catcher or the one's you stick in freezer for the liquid stuff to freeze? My bong has a foot tall ice catcher. fills about a cup and half full of ice and I would never forget about smokin it.
Yeah, that barely noticeable part is what almost killed me the first time I ever hit a bong with ice in it. I didn't know there was ice in there, so I ripped it, couldn't feel the smoke, so I kept ON ripping it...nearly coughed up a lung.