The act of being rapjacked is when you are driving to Shamrock Fest, listening to music using an FM tuner, and a radio station overpowers your FM tuner, forcing rap to be played on the radio, blocking out the music you were just listening to. This is usually resolved temporarily by changing the frequency on which you are broadcasting. Be aware, however, that this is only a temporary fix, and a Rapjacking may occur at any time, on any channel, so you should always be alert and ready to change the frequency.
Brandon, quick, change the channel! We're being Rapjacked!