Man back in the day my friend had a real hi-lighter pipe which be bought from a smoke shop.

It was the shape of a real hi-lighter, worked really well, but the back end would 'Pop' open and there would be a small ass one hitter attached to what came out. It was the best concealed pipe ever. He was searched at school and they never found it.

The only thing is if you held it, it was a little heavier then normal since the thing that came out was some sorta metal.