Arc
Shoot a melon out of a bow and it will fly in a steep arc. Melons are too heavy to fly straight, after all.
Imagine shooting a really heavy melon out of a bow. Watch it make an arc through the air. Trace the arc with your finger.
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Shooting melons in an arc is something little 子's (こ) love to do. It also helps that when they come down from the arc they smash all over the place.
Imagine being a 子 and watching melons fly in arcs all over. Imagine a little 子 version of yourself giggling and clapping your hands with absolute glee.