According to clickondetroit:
“Little Caesar’s is claiming that a Royal Oak restaurant is infringing on the copyright of the slogan ‘Pizza -Pizza.’
The pizza company has used the slogan for more than 30 years to tell customers they could get two pizzas for the price of one.

Jim Rasor is representing the owners of Pronto! Restaurant. He said a member of the Ilitch family, who own the pizza company, recently dined at the restaurant and noticed ‘Pizza Pizza Pizza’ on the menu.

Rasor said something must have been mentioned to the pizza company’s attorneys because the restaurant has received a letter alleging copyright infringement.
He said Little Caesar’s says the restaurant’s menu is confusing to customers because it so closely resembles the slogan.”