With 2 players go to Radiation. Then one of you go to where you operate the door switch (operate the doors so it is open).

Then the other player go down to the doors and lay down just right off the edge.

Now the person that is by the door switch operate the doors again. When the doors are shut go down to the doors and you'll see one of the players legs or head sticking out!

If you do not see that, then go down under the doors and you might see them. And then if you can't see them you didn't do it right.