The one customer I will always cherish from my time in tech support is the one that screamed at and abused me the most.
She was a detective working on a big murder case, who couldn't get connected to the Internet through the ISP I was working for at the time.
As I went through all the normal troubleshooting procedures, I discovered this lady was the cell phone only type. When I told her she'd need just a plain old phone to connect to the 'net, she went ballistic, like I had mortally insulted her honor, and seven generations of her family's honor. She called me every name in the book, threatened lawsuits, I think she was spitting a lot. She didn't know you needed a phone to connect to the 'net!
I couldn't resist. I walked her step by step through our installation guide, taking time to point out every icon with a picture of a phone in it. My tongue caressed every word that had even the slightest relation to a telephone. She got calmer and calmer throughout the process. I'm good at talking people down.
However, I simply had to get the last word. I told her, as sweetly as I could, "If I were a detective, I'd call these things clues." I ended up losing the customer, but she had given me such a perfect set up I found myself unable to resist.
That was three years ago. The murder goes unsolved.