to quote from wikipedia:
"In May 2007 the song's campy music video became the basis of an Internet phenomenon known as "rickrolling". It took its name from a 4chan meme known as "duckrolling", a prank in which someone would post a blind quote to a post allegedly relevant to a discussion that upon viewing would prove to be a non sequiter - specifically, an image of a duck on wheels. Similarly, in a rickroll a poster provides a link they claim is relevant to the topic at hand which actually takes any one who clicks it to the Rick Astley video. The practice eventually became widespread enough to attract some coverage in the mainstream media."
here is the link to teh article
so there you have it. You trick people into click a rick astleymusic video. We are all familiar and have all been caught in the trap.
so here si the thread to discuss how you catch people and hwo you have been caught.
here are some of the videos people use.
also there is one that has the window jump around and dialog boxes with the lyrics pop up, but i can nto remember the link.