Try this practical joke on someone you hate. This will only work if your mark doesn't lock the doors on his/her car or you have keys. Buy two pieces of fish. Put one in the freezer. Take the other one and put it in a tightly sealable Glad plastic container you don't intend on keeping. Do not use a zip lock bag. If it gets a hole in it your fucked! Tape the container closed along the seem with packing tape and place it in a garage or tool shed off the floor. After about a week get both pieces of fish and take the one from the freezer out of it's package and toss it on the floor in plain view of the car of your mark. Untape the plastic container and pull the top off. Don't forget to hold your breath. Hide the bottom of the container with the fish underneath one of the seats. This will work best if you can do it so the car can sit for awhile. Roll the windows up if you can. When your mark sees the fish on the floor he/she will think that is what smells.