In the Warehouse in freestyle mode, go on top of the biggest jump. You should see two holes in the wall. They lead to other rooms and levels. To get to one of those levels, go over a large green crate is located (not the area with a lot of green crates, just the one). Go off the left edge of the jump into the corner with a large metal sheet. Bail or just fall when you hit the metal sheet, and it will reset you in a room with a huge quarterpipe, a big tabletop, and two holes in the wall. Note: This does not work every time. Hit the very big jump at a angle, as if your coming from all the big green containers. If hit correctly, you will fly onto the platform and reach the secret area.