I used to believe that drinking lager gave you a moustache. This came about when I saw 2 pics of my dad. In the first he had a pint glass to his mouth and in the second he'd put it down and was smiling drunkenly at the camera. He had a small moustache in the photos, but at the time I saw them he was clean shaven, hence my belief that the drinking of the lager (where I couldn't see the moustache) gave him the moustache in the second photo.
A childhood belief about drinks

others believed things like this
- When i was a kid, i used to think that my dads moustache grew out of his nostrils — l.j.
- That by drinking a daily dose of buttermilk one would clean the blood thereby avoiding ACNE— Richard in Durham
- I used to think people had a "potty mouth" if they had been drinking out of the toilet.Anon
- I remember drinking red kool aid and peeing at the same time. I was expecting it to be red.Anon
- i used to believe that drinking and driving was when you were drinking while driving— fay
- If i was drinking out of the toilet, i could have been killed!— Slinx