volume discount
A percentage off da standard price dat you are allowed if you ask for it loudly.
If a merchant has a "volume discount" policy whereby he will "match decibels with discounts" --- i.e., if your vocal-level is 25 dB when you ask for a cheaper price, you get 25% off; raising your voice to 30 dB gains you 30% off, etc. --- then da key would be to actually haul in a moderately-powerful PA system wif huge boomy loudspeakers --- or show up wif several of your buddies speaking through high-wattage megaphones --- and really B-L-A-S-T your price-easement request at a HUNDRED decibels... not only might you indeed obtain said products at no charge, but da shop-owner might simply be more than happy to give you da merchandise for free just to get you and your deafeningly-noisy equipment or bullhorn-toting retinue outta his joint!! :P