These are sayings of Swedish children. Daniel gave me their source: Gamla tanter lägger inte ägg([old] Aunties don't lay eggs) by Mark Levengood and Unni Lindell. Read also the ones that Daniel added in the comments.
On Human Bodies
1. The most important part of us is the toes. They are used for steering.(Mattias, 6)
2. The bodies of ghosts are not made of flesh. They are made of sheet material. (Olav, 5)
3. The nose is actually a muscle for breathing, but it can also be used to transport snot.(Emil, 6)
4. If you walk in the woods and your brains fall out, you won't be able to find your way home
because you can't think clearly. (Marten, 4)
5. If we had no bones we would be reptiles, and shoe stores wouldn't sell very much.(Mikael,6)
6. The brains are for keeping the hair attached. (Nina, 5)
7. People have many sorts of skins. The foreskin is in the front, the backskin is in the back.
(Therese, 6)
8. If you have no nerves you work better and run more errands. (Harald, 7)
9. My mom is awfully pretty; she has such long tits. (Mia, 4)
10. The stomach is very important. If we didn't have it, food would run down our legs. (Lars, 6)
On Animals
1. The cows which are the friskiest and shake their udders the most make youghurt.(Allan, 5)
2. The body of animals usually lies behind the head and the paws hang on the underside. (Ketja, 6)
3. The name of the dog's mother is dog and the name of the dog's father is dog and the children's name is puppy and the dog's name is dog. (Allan, 5)
4. Mother's name is hen and father's name is male, the children are lambs and the grandchildren are eggs. (Stefan, 6).
On Religions
1. When God died, he was allowed into heaven like all the others. So there he stayed. (Erik, 5)
2. Jesus was first a pupa, then a bug, then he grew wings and became a god. (Kate, 6)
3. Only the soul dies. The body continues living. (Elisabeth, 7)
4. When you die you get an eternal life. This means that when you die once, you can't die again ever, even if you die one more time. (Elena, 9)
5. When it is twelve o'clock, everybody turns towards Mecca and chews on the fringes of the
carpet. (Raymond, 7)
On Grandparents
1. Grandma was in great-grandma's belly, mom was in grandma's belly and I was in mom's
belly. But I have nothing in my belly except meatballs. (Helene, 6)
2. A grandma is an auntie who used to be a mother when she was a child. (Caroline, 6)
3. A grandma is the one out of which the whole family came. So it is no wonder that her skin
is a little loose. (Kristina, 7)
4. Grandpa lies under a tombstone. We pat him on the stone and once we dug some onions
into the ground so that he'd have something to bite. (Siri, 5)
5. A mother-in-law is a grandmother who is not the mother of the person in question.(Hannele, 6)
6. A mother-in-law is what you get for marrying a stranger. (Pal, 7)