Steps to follow:
1. Buy 4 pigs from somewhere
2. Label them as #1, #2, #3, and #5
3. Let them loose in a public place preferably in a mall(they got some security)
4. Enjoy the show as the security personnel run around looking for the #4 pig......

Dial up any random phone number.
You: "Can I talk to X?"
They: "Sorry. Wrong number"
Wait for a couple of minutes and dial back the previous number.
You:"Can I talk to X?"
They (obviously irritated): "I told you it's a wrong connection."
Call back the same number after 5 minutes.
You:" I'm X speaking. Did somebody call you for me?"
Disclaimer: Do it at your own risk!

Disclaimer: I am not asking you to follow these ideas.
Walk to a small child resembling you and tell them you're him/her from future.
Call someone to tell them that you can't talk right now.
Walk into a group of people chatting casually and then say, "Are we going to kill him or what ?"
Bring an extra pair of shorts to pool, dive in and let the extra pair float.
Put a post in every mail box reading "I know where you live."
Go into a crowded elevator and say, "I bet you all are wondering why I gathered you here."