add_filter( 'avatar_defaults', 'newgravatar' );

function newgravatar ($avatar_defaults) {
    $myavatar = get_bloginfo('template_directory') . '/images/labrats-gravatar.jpg';
    $avatar_defaults[$myavatar] = "LabSecrets - Booyah!";
    return $avatar_defaults;
}

Change the name of the image file from "/labrats-gravatar.jpg" to whatever you want to call the image you upload. Be sure that it is sized to 128x128px and is a .jpg format.  Be sure to upload this image file to your theme directory in the "images" folder.

If you want, you can change the description text "LabSecrets - Booyah!" below as well.

Change the default Mystery Man Avatar

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