Trolls are alive and well, and not just living under a bridge anymore.
One of the things I do for fun is dabble with electronics. And the electronics I dabble with come in the form of things I can control with an Arduino. You can make all sorts of neat stuff with some wire, resistors, servos, LED's, piezo buzzers, etc. You use a program on your computer to program and upload 'sketches' to your arduino board to make it do different things.
I was messing around with my pile of components, making some funky LED designs when I got bored. I was playing with the program and found some pre-compiled programs that were distributed with the Arduino software. They are designed to give you the basics of making circuits.
So, out of a sense of nothing better to do, I loaded sketch one and built it. It was a blinking LED. Number two was adjusting the brightness of an LED with a potentiometer. Three was an RGB LED, and so on. They were all simple, and I didn't learn anything new.
Until I got to number eleven. This was where the started teaching you how to use a simple piezo buzzer. I set up the circuit like they described, and uploaded the sketch and expected to hear the promised 'Twinkle Twinkle Little Star'.
No. The person who programmed the sketch turns out to be a troll. I did not get the promised 'Twinkle Twinkle Little Star'.
I got Rick-Rolled.
The sketch sent the first 18 notes of 'Never Gonna Give You Up' through the piezo buzzer I had connected to my breadboard.
Well played anonymous coder, well played.