Why do people tie old shoes and cans on the back of newlyweds' cars?

United States
@tammyr (5879)
June 9, 2008 2:46pm CST
This is an old tradition that lots of people partake in, but do we know why? I know it makes a lot of noise so everyone will look at them as they travel to where they are going, but I'd like to know where the tradition came from. Where did it start? WHY??? Also are there any other wedding traditions that you have in your family? What are they?