The 80s Rick Astley hit, "Never Gonna Give You Up," was long forgotten. That's when 4chan found use for the song, in its memefied remains (see what I did there?). It's become a huge sensation, so I decided to do a basic piano arrangement so that people can Rickroll each other with an irritating, personal touch.
If you want to use my arrangement as a RickRoll unto itself, I made a page with a large autoplaying video and a misleading URL:
http://www.benlandis.com/2008-article-012.htm
If you want to learn the arrangement yourself, check out the sheet music. Though it's called the "Piano Rickroll," I put in chords for guitar/bass accompaniment and there are lyrics for the sections included. If there's widespread interest in other arrangements (e.g. rock band, faux-serious acoustic guitar, polka), let me know and I might draw up some more sheets.