Well, I don't know. That's how it's always been round here, I guess. When I was introduced into the wonderful world or marijuana, my friends all called their pipes bowls. At first, I called them pipes, too. But, they corrected me saying, "Pipes are what you use for tobacco, bowls are what we use for weed." After that, I just started saying bowls, I guess? lol

As to bongs, when we do use a bong, we'll say, "You wanna pack a bowl in the bong??" or something similar to that.

Maybe it's just stupid Indiana slang?? lol