Okay, I have been rickroll'd on a prior occasion, so I was fortunate enough to know what this link was for, and chose not to put myself through that pain again.
The difference? When I was rickroll'd before, the subject title had "NSFW", for Not Safe For Work. I knew not to open it at work, on any computer other than my own, and not in front of my wife and/or kids.
So please, if the post is not safe for work, put "NSFW" in the subject line with the subject.