At one of our favorite little dive restaurants in Montebello (East L.A. adjacent ;) - my sisters and I love the Camarones Ahogados (drowned shrimp) - it is shrimp"cooked" in Lime juice, cilantro and and slices of Jalapenos - a ceviche of sorts. Ceviche is a dish that is cooked in acid, such as lemon and/or lime juice. If you use fresh shrimp, or other seafood, you should be fine. If you are even slightly concerned about freshness, you may be better off cooking them by a more traditional method.
I like to add 1/2 bottle of Chef LaLa Homemade Tequila Lime Marinade to 2 pounds of large raw shrimp, they are usually "cooked" (pink and opaque) in around 20-30 minutes.
