San Diego Zoo Wildlife Alliance garbs sheep in animal costumes, to help illustrate the irreplaceable nature of wildlife once it's gone. Here's AdAge.com's description of this advertising campaign:
Created by Goodby Silverstein & Partners, the idea revolves around imposter sheep posing as wild animals such as lions, giraffe, rhinos, penguins or peacocks, to get across the message that "you can't replace wildlife once it's gone." Videos and outdoor ads reveal the sheep dressed up in ridiculous guises while radio ads put a fresh take on the lyrics of "The Lion Sleeps Tonight."