ad verb. to shop pre emptively before actually having the money. Similar to pre gaming before going out, its the preperation for the event of getting paid. Pre shopping can consist of online shopping cart filling, pressing the "buy now, bill later" feature, putting mass quantities of clothing on hold at your favorite stores, and spending your future paycheck in your head. Obsessively.
"Dude, I know I dont have the job but I've been pre shopping the salary all night!"