This is lots of fun and whenever I do this it always creates pandemonium in the crowd.
I have two full size dummies left over from my old entertainment company. They are hideously old looking male and female characters that I used in an Over-the-Hill birthday party routine.
I started using them in customer service presentations where I demonstrated various acts of violence on the dummies to illustrate what some nasty customers deserve. People in the crowd who gave correct responses to the "proper" way to respond to nasty customers got to come up on stage and kick, gouge, body slam, bash the dummy with a sledge hammer or do any socially unacceptable thing they wanted to do to the pseudo customer.
In the right situations with the right crowd, this will bring down the house. Soon the dummies were being thrown around the room like a teenage rave party and the place was a mad house.
TO MAKE A DUMMY
You may be tempted to use one of your colleagues or spouse for this, but please refrain and do it this way.
Buy a pair of long underwear and sew the top and bottom together(you may have to get someone handy with a sewing machine to help you with this). Stuff the body and arms with newspaper or for a heavier dummy use foam padding like you would find at an Army surplus or camping store.
Visit or get a catalog from a costume store like Morris Costume in Charlotte, NC. Get a hideous looking rubber full head mask,and a set of hideous monster gloves/hands. Stuff these and sew them on the dummy.
For feet, you can use monster feet or to save a few bucks just sew on some stuffed socks and old shoes.
Just for fun I would put the dummies in seat belts in my car and hook a yardstick to the chin of the dummy in the passenger seat. This yardstick could not be seen by the driver in the car next to me. At stop lights I would pretend to talk to the dummy and move it's head with the yardstick. I had to quit because I was sure I was going to cause an accident.
If you want to freak out your neighbors, put one of the dummies in your trunk, throw it over your shoulder and carry it into the house at dusk. You get extra points of this if you happen to be digging a hole in your back yard at the time.