The Apollo astronauts went into space equipped with very few things one might deem necessary for a trip so far away, but they had very little room to work with.
One of the bits of kit they never left home without was a can of shark repellent.
You are correct in pointing out that there are no sharks on the moon. There is no water on the moon; it is an inhospitable place for sharks or indeed all marine life of any kind. The average shark wouldn’t find it very comfortable on the moon as there would be nowhere to swim, nothing to eat, and it would also be quite cold. The astronauts didn’t know what they would find on the moon, but they could be pretty certain not to run into any sharks. Little green aliens — maybe. However, it’s hard to buy a can of alien repellent as we do not yet know what repels aliens. A can of Reddi-Wip would probably do the trick. Barring that, a good blast of Aqua Net might work.
So why did NASA supply its astronauts with shark repellent?
Because back when Saturn V rockets launched spacecraft, the only way to return to Earth was to splashdown in an ocean, the fall from above only slowed by a parachute. Upon hitting the water, there was a very limited amount of time for the astronauts to pop the hatch and climb out before the capsule sank. Waiting for the rescue vessel to reach them was in many ways the most perilous part of the entire journey due to the possibility of being eaten by sharks. This would have been an enormous waste of an astronaut, which require many years of training to send to the Moon, not to mention the expense of their nifty spacesuits.
This astounding tableau celebrates Man’s achievements in the space program rendered entirely in graham crackers and chocolate. Please note that the name of the rocket — the US CHOCOLATE — is pure whimsy; none of the actual Saturn V rockets was so named. Also fanciful is the notion that the whole ensemble, complete with launch boosters, ever made it to the Moon; only the topmost portion did. You can see the astronauts peeking out of its windows.
It’s also worth pointing out that the Moon is not made of tinfoil. Cheese, yes: Reynolds Wrap, no.
The rocket was fondly named a "candle" and the landing module the "Eagle." This is because rockets are explosive devices with a very real possibility (and history) of incinerating people who ride atop them. Eagles nest in hard to reach places, though none as tricky to secure as the Moon. To "moon" someone is to present to the world at large one's bare buttocks, preferably out the window of a moving vehicle, and is generally considered a vulgar act. There is no evidence the Apollo astronauts took the opportunity to moon everyone on Earth, but Verne Ricketts, the architect of this chocolate fantasy, certainly did.
Chocolate Fantasies, Verne Ricketts, Leiba, Inc., 1985
Also from this book: Chocolate Hot Tub, Chocolate Hanukah, Chocolate Nativity, A Chocolate Tragedy, Animal Crackers