Drive up to an intersection and start honking your horn. Other cars will join in the fun and honk as well. Get close to a police car and honk your horn. They will run their siren to honk with you.

When stopped in a car in a large traffic jam, tap out the rhythm of the musical phrase "Shave and a haircut" on your horn. Another car in the traffic jam will answer it with the standard two beep "two bits" response.