"there's a place in Portsmouth, NH called Macro Polo
http://macropolo.com/ and they had the most real-to-life dog poop for like $3. I bought one, and it freaks everyone out when they see it as it looks so real. I can only imagine 20 kids running around placing them and freaking everyone out.....no n oise from the poop, but the noise from all others would be amazing, lol"
What would be even funnier would be to place a pile of real poop after everyone got over seeing all the fake stuff....and watching them pick it up!