mcdonalds 1970s ad african american

BuzzFeed's Copyranter recently posted this 1976 McDonald's ad that clearly attempts to cater to African Americans.

But, the copy seems strange. It's the line, "Do Your Dinnertimin' at McDonald's," that really gets us. We're pretty sure that "dinnertime" has never been used as a verb. By anyone. We think it might be a mistaken attempt at some sort of vernacular English spoken by African Americans, and the effect is a bit off-putting.

Do you think this ad is racist?