Forrest Gump, during his second visit to Washington, D.C., is unwittingly swept into a line to participate in an anti-war rally on the National Mall. He is invited to speak to a tremendous crowd of people opposed to intervention in Vietnam, and begins to do so, but just as he does, the PA system is unplugged by a policeman who is hostile to the movement. Much of Forrest's speech remains inaudible to all but the few people in his immediate vicinity (unbeknownst to him) until the rally organizers finish plugging the PA system back in, just as he concludes his speech. This is met with complete silence, until Abbie Hoffman, who heard every word Forrest said, reveals that he was moved by the speech.
Then, Jenny Curran, now a hippy, runs into the Reflecting Pool to meet Forrest again. He runs to meet her as well, to thunderous cheers and applause.
According to Tom Hanks, what Forrest says when the microphone gets unplugged and you can't hear him is "Sometimes, when people go to Vietnam, they go home to their mamas without any legs. Sometimes they don't go home at all. That's a bad thing. That's all I have to say about that."