Go to where the Iron Skull on Sierra 117 is and jump down into the corner.

Have a friend stand on top of you and press A quickly.

Your friend should be on top of a rock glitching out, then you jump off into the water and you should respawn near him.

Follow the wall all the way around the area and look to the left, away from the water, and there should be a monkey.

This should work if done correctly.