We used to light candles and lie down on the slabs to creep out any newbies that we would bring down there. It backfired once because someone came to the entrance while we were down in the crypt and we had little birthday candles lit all over the place. It's hard to hide and pretend no one is down there when they see candles everywhere (that only burn for 5-10 minutes max).
One night, the place filled with people who came in after us. They got too wild and too loud, knocking over things, shouting and screaming. We knew it was only a matter of time before the cops came so we left for the road. On the way to our car, we walked through the Pohick Church Cemetery and rang the huge bell in the graveyard. Man, it was really loud! We ran like scared rabbits, running into each other and tripping over grave markers. As we pulled away in our car, we saw a Police paddy wagon pulling onto the access road. Good timing for us!
It sure was a lot of fun!