There She Blows!
The first military submarines were not very high tech. Even flushing the toilet was tricky! Compressed air was used to blast the toilet's load out of the sub. Since the bubbles might give away the sub's position, toilets were only flushed at night. If you turned the wrong valve, a day's worth of poop would blow into the sub!
Can you find the seven horrified faces hiding in the blow up?