Does anyone know what the "Luigi Discount" is?

First of all, if Luigi even exists I'll fall off my chair.  It's a marketing ploy.  Providers likely pay a premium to be listed as a Luigi girl.  The providers would like to track how well the ad pulls, so the lure of a discount is offered to get the client to mention the Luigi girl ad.  Just my speculation as a marketing guy.

Thanks for the clarification