Yeah, I've been the contributor to a random act of kindness...

On my way home one evening, I heard a car blow a tire. A young, attractive woman got out and asked if she could borrow my cellphone to call the auto club. Instead, after telling her to carefully move the car to a quieter side-street, I changed her tire for her. She was so grateful that she gave me her business card and said she'd buy me a drink.

She stood me up.

Nowadays, I think twice before I do a favour for someone. I still do nice things on occasion (e.g. give way to another driver who is obviously in a hurry, or hold the door open for the elderly), but I won't go out of my way as often as I used to.

cheers
Hachiman