It's amazing what people believe and how they can make you briefly believe it might actually be true too. What daft things have you been told over the years? I had a guy tell me that the colour of a man's eyes change after he masturbates. I said "hang on, you mean the shade of the colour changes, and not the actual colour?". He wouldn't even let me have that. He said it with such confidence that I doubted my better judgement.
I had someone else tell me that it's a misnomer that, under Irish law, a company can't make an employee work more than 6 days week. It's something I hadn't read about in years so I let him have it.
Another time when playing charades (and this was just 2 years ago) I had someone mislead me for about 10 minutes because he thought Arnold Schwarzenegger WAS a politician, and WASN'T an actor! I kept thinking "okay well if can't be Arnold Schwarzenegger" for the whole 10 minutes. How can you ever not be an actor after being an actor anyway?