How do Harry's escorts plan to confuse the Death Eaters when Harry and the escorts leave Privet Drive in the novel, Harry Potter and the Deathly Hallows?

Harry's friends announce that in order to throw the Death Eaters off Harry's trail, some of Harry's friends are going to drink Polyjuice Potion. Polyjuice Potion is activated when someone's hair is dropped into the liquid. When another person drinks it, he or she becomes the double for a limited time of the person whose hair is in the potion. Harry protests this plan, but his friends will not listen.