In retail, a customer who feels they are absolved, for whatever reason, from paying the full retail, or even sale price, of an item. They are ruthlessly aggressive, cutthroat, and Grade-A social bottomfeeders, of the lowest order. Often they will use every lie or excuse in the book, in order to garnish themselves a deal. They will claim a product is damaged, when it is not. They will claim to be family of staff, when they are not. Females will attempt to use sexual charm, while males prefer verbal aggression, to try and break down a salesperson. Easily spotted. Often found standing in the middle of the store, yelling at the top of their lungs, and making an ass of themselves.
"If that 'professional bargainer' makes a purchase from you, make sure you hit him up with the hidden 'PAIN IN MY ASS' tax. He has it coming to him!"