In the mid-1980s DC Comics and the very successful Canadian store Zellers released a chain of commercials featuring Batman and Robin along with various other villains like The Joker and The Riddler. Those are just 2 of the many featured in the series of advertisements. DC Comics agreed to do these commercials as long as they would heavily promote their products and espicially Batman products because of how the 1989 Batman film was in post production at the time.
The plot of these commercials features Batman and Robin being told in the Batcave that one of the villains of Gotham City is "ripping off" one of their customers with expensive prices for their toys. So Batman and Robin come in and scare off the villains and mentions the LAW OF TOYLAND which basically means if there is a lower price on one of the toys that Zeller has somewhere else, they will match it or go lower. They continue to advertise Zellers and the ad ends.