Sierra 117 Vacation

The Sierra 117 Vacation is a glitch that allows you and a partner to exit the boundaries of the Campaign level, Sierra 117.

Tutorial
To perform this vacation, load up Sierra 117 on Co-op from Rally Point Bravo on any difficulty. Play through the way you would normally, except once all the enemies are dead, dont free Sergeant Johnson. Instead, head up as if you were going to get the Iron skull. Once up there, have you and your friends Butterfly onto the wall above. Once up there, have one player commit suicide, while another one crouches by the rocks. If all works right, the respawning player should spawn above the other player now being stuck in the invisible wall. The player(s) not stuck in the invisible wall should proceed to commit suicide, and should respawn outside the map.

What you can do
Once outside, you can see many things. You can see the Lone Caveman, the Entrance to Crows Nest, and the Stairway to Heaven. You can also walk all over the map, and not to mention glitch the f*** out of your screen from all of the Hall of Mirrors effect too. Finally, unlike most other vacations, if you want to go back and finish the level, you can without restarting from last checkpoint with this vacation.