This is a very strange one, I will be surprised and somewhat relieved if anyone else believed this.
In elementary school I thought that people's spit had a specific smell and that if I drank from the same cup or if someone accidentally spit on me while talking my spit would smell like theirs.
A childhood belief about general

others believed things like this
- I used to believe that big grasshoppers would spit tobacco at you if you got too close to them.— Uni
- I used to believe that if I poked my grandfather in the belly-button he would spit out quarters. — Justin
- My Dad told me that Soy Sauce was made of grasshopper spit! I didn't eat it for YEARS!— TawnyKat
- I used to believe that when I farted, i could smell up all the stench before anyone else could smell it.— Tim
- I used to believe that I could smell when it was going to snow.
(I still can!)— sw - Skunks smell bad because they eat garbage.— Isabel