Drinking that is done before going to an event where drinks that you will purchase are very expensive. Often occurring in vehicles and parking lots before the event while watching for the police.
Similar to Rocking Out Listening to progressive music but imitating the excellent musicianship often while moving your upper body to the music.
Actions often overexaggerated
"Hey, WTF are you doing?"
"I'm just progging out, although your feeble mind does not understand the insane complexity of my progressive music"