Taco Bell is testing Doritos Locos Tacos, in which the ingredients are similar as Taco Bell's other offerings, but the outside is made of the iconic tortilla chip.
There has been a Facebook campaign (aptly titled "Taco Shells Made From Doritos Movement" "for a while but according to the page, they were not informed that the product is now actually in development. At the moment, only Toledo, Ohio residents can test it out but in the meantime--if this interests you--maybe you can be bootleg and make your own tacos but with store bought Dorito's, just to see how it might taste (there's probably people who have been doing that already).
It is unclear if or when this product will be nationally available, but in the meantime, you can check out the following video and see what this man thinks:
Via Slash Food