Guacamole looks gross. You could say it was mashed up frogs or swamp scum or something.

I make no bake cookies and shape them like turds. Then buy a litter box and pooper scooper and fill the box with Grapenuts cereal. Place the turd cookies in the "litter box" and make them scoop for "poop". That was the hit of the party the few times I made it. Didn't do it last year and I had our guests asking where the cat crap was. They missed it! lol I even made a sign that said "this treat was specially made by Domino, Kahlua & Prowler". (our cats)