- Have a friend call you, accept the phone call.
- Hit the menu button and goto Contacts
- Hit the back button until you hit the home screen
- Goto Settings, then Goto Accounts & Sync
- Delete (click on contact, then "Remove Account") every account except for your Gmail account
- End phone call
- Type in your username (WITHOUT @gmail.com) and your password
- Make a new security code.
- Re-add synced accounts.
Enjoy! Note, this worked on Android 2.1, I don't know about compatibility on other versions.