Silly juice or Formula?
Go to the liquor store knowing how much you're going to spend and bring only that amount of cash. Fill your shopping cart with beer and liquor. Also pick up a pack of diapers, some baby formula for and a soother for shits, with no intention of purchasing them. Get to the checkout, act distraught that you don't have enough money for the booze and the baby stuff, think for a good 10 seconds, then go put the baby shit back on the shelf. Laugh hysterically at the mortified look on the cashier's face. Works best on middle aged women.
Have your friend film it and post the video in the comments section!