'Flintmobile' is the signature car used by comic characters Flinstones and was stolen from the shop in last December, reported People magazine.
The teenagers, who were shot by CCTV cameras while stealing were only found guilty in January but the owner did not agree to press any charges against them.
Instead the trio was asked by the owner to promote the shop on its busiest day, Free Comic Book day, which is celebrated on the first Saturday of May.
The other two dressed up as Fred, Barney from the comic. From 10 am to 7 pm the three teens danced, waved, held signs, and lured drivers into the store's parking lot.
