Okay, my obsession with the Rickroll has gone too far.

Schroedinger's Rickroll: A link is implemented to a script with a single argument (the argument being the intended destination of the link). The script's code serves a single purpose: redirect randomly to either 1) the destination listed in the argument or 2) a Rickroll. As the link itself is variable before it gets executed, pre-click, it can simultaneously be considered both a Rickroll and not a Rickroll.