A friend of mine tells a great story about how when she was little her dad had told her that when the Ice cream van came round and rang his bell, that it meant that he had run out of ice cream. She belived this for quite a while apparently.
A childhood belief about ice cream vans

you weren't the only one
121 of you believed this
- My parents told me that when the ice cream van was playing music, it means he's run out of ice cream :(Anon
- I used to believe that if the ice cream truck was playing music, it had sold out of ice cream.— Deprived of ice cream
- My dad told me that ice cream vans only play music when they have run out of ice cream. Anon
- My Mum told me that when the icecream man played his music it meant that he had run out of icecream!Anon
- when i was a kid my mother told me that when the ice cream man was playing his music he was out of ice cream— Lynnzea
- My mum used to tell me when the ice-cream truck turned on his jingle, it meant they had run out of ice-cream!Anon