This is a very similar achievement to 'hoff the charts'
First you must complete the EE for Rave in the Redwoods.
Guide here:
Once you have done the EE, you must go back to the main screen and enter a lobby, once in the lobby enter the following combination on the D-pad
Right, left, left, down, down, right
If done right you will see Kevin Smith appear in the bottom-center of the screen.
Once the game starts you should be playing as Kevin and the achievement will pop.