First, acquire a baby. The old-fashioned way is cheapest, but labor and time-intensive (may take up to 9 months). Depending on where you live, you may be able to adopt one with a minimum of fuss. If you live in a large city, check garbage cans near hospitals.
Now that you have a baby, hail a taxi. Again, the exact procedure varies from place to place, but generally includes at least one of: waving; yelling "Taxi!"; throwing yourself in front of the cab (WARNING! Do not try this in New York City); throwing money in front of the cab; small arms fire.
Get in the taxi with the baby and tell the cabbie what address you would like to deliver the baby to. Get out once you're there, being sure to tip extra to compensate for the fact that he will have to remove baby vomit from the back seat. Ring the doorbell and/or knock on the door, and when the recipient answers, say "Here's the baby!"
Better yet, just forget the whole thing.