Once in a park in my hometown, we got offered bud that we didnt expect, so we decided to make a bong, we had a water bottle to use but we couldnt think of anything to use as a stem. we walked around the park for about an hour looking for something till i came up with the idea to use a pen (it was after school so we had pens)
i burned a wider opening in the bottom, and my cone-piece just happened to fit perfectly in the other end.
(it screwed in cause it was the kinda pen that the top screwed into the bottom, and my cone-piece had a screw bit at the bottom.)

Then there was the time that i went out with a dealer, and he suggested we go get high, so where in a different park, and he just goes to a hedge, reaches in and pulls out a homemode bong.
Just out of nowhere, he said heaps of people smoke there and he jsut thought it would be there.
There was even a plastic mix bowl there...