I used to believe that if you ate a watermelon seed, a watermelon would grow inside you. I got this idea from a Rugrats cartoon where Chuckie swallowed a watermelon seed, and the other babies had to shrink and go inside him to stop it from growing. lol.
A childhood belief about seeds

others believed things like this
- I use to believe (thanks to my Mom) that if I swallowed a watermelon seed a watermelon would grow in my belly.Anon
- I used to believe that if you ate a watermelon seed you would grow a watermelon tree in your stomach!!!— Eskimo
- If you swallowed a watermelon seed it would grow in your belly— Rachelle
- when you eat the seeds from a watermelon a watermelon will start to grow inside your stomache.Anon
- I used to beleive that if you ate a black watermelon seed a tree would grow in your stomach— anonymous
- i used to think if you ate a watermelon seed then after a while you'd become a watermelon
— olga british-girlyman