If you are scared of GreenPois0n RC5 animated Boot logo of rotating skull then here is how you can add you own custom animated boot logo to your iPhone.
Start Cydia and then search for BootLogo, in the search result you will find animated custom boot logos like Apple Boot Logo, iPod Touch Boot Logo, Shattering Apple Boot Logo.
Install any one or all of the animated boot logos. As you install any of the animated boot logo, you will automatically get the BootLogo app installed on your iPhone. Now simple go to your iPhone settings from Springboard and look for BootLogo option. In BootLogo you can select the animated boot logo of your choice.