We see the real inception of this term with the creation of the movie, The Goonies which debuted in 1985. This term was coined by the character known as Mouth, and was played by Corey Scott Feldman. The line was simply yelled by Mouth, when the Fratelli's were catching up to The Goonies in the caves.
Mouth: "Senior Jerk Alert!"
by Nick Flynn January 24, 2008
Something you can say whenever someone you disapprove of walks in the room. So basically it will be said often and repeatedly. Can also be used for someone that you see on T.V., or in a magazine etc...
Whenever George 'dubaya' Bush is on T.V. I say Jerk Alert and everyone laughs.
by kitty April 08, 2005