In my early 20s a neighbour who really had it in for me spread a rumour that I was a prostitute and a drug dealer, based on the fact I had 'under age boys and men in and out of her flat all day'...
These were in fact my SISTER, a family friends DAUGHTER who had shaved her head for charity, and a platonic male friend and my actual boyfriend...
The drug dealer part came about because I'd found a needle down the back lane a lot of the residents kids would play in, had called the council to do a clean up and warned neighbours not to let their kids play there until it had happened (backed up a day later by the council sending a letter round).
The most hilarious though was on catching up with a friend after some decade or so of being out of touch.. I discovered I had apparently always been in love with a mutual friend of ours, who I had had a brief (5 months?) relationship with when I was 18 or so...
It was interesting to hear that apparently, I still loved him, he was the love of my life and I'd never gotten over him...
I hadn't thought about him in 10 years and had been living with someone else for 9 of them!