Add custom tags to the 'pre defined tags' section

yikes-easy-forms-for-mailchimp-custom-default-value-tag.php

<?php
/*
*	Add a new custom tag to the 'pre defined tags' section
*	@ Change 'tag', 'description' and 'title' to suit your needs.
*	@ $available_tags - the default pre-defined tags available out of the box
*/
add_filter( 'yikes-mailchimp-custom-default-value-tags', 'add_new_pre_defined_tags' );
function add_new_pre_defined_tags( $available_tags ) {
	// define a new array, with our default tag data (note: to create more than one, simply copy and paste what is below and alter the values)
	$available_tags[] = array(
		'tag' => '{YIKES_Example}', // tag that will be parsed
		'description' => '<h4 class="tooltip-title">Yikes New | <small>{YIKES_Example}</small></h4><hr />' . __( 'This is the description that appears in the tooltip, when hovering on the question mark icon.' , 'yikes-inc-easy-mailchimp-extender' ), /// tool tip content that appears on hover
		'title' => 'YIKES Example' // title of the link (on hover, used for accessibility purposes)
	);
	return $available_tags; // return the new tags
}


/*
*	Process the custom tag, and populate the field with some value
*	@ $tag - the tag that you would like to parse
*	@works only with email, text and number fields
*/
add_filter( 'yikes-mailchimp-process-default-tag', 'process_new_pre_defined_tag' );
function process_new_pre_defined_tag( $tag ) {
	// set up a conditional so we only parse the tag we need
	if( $tag == '{YIKES_Example}' ) {
		// confirm the user is logged in
		if( is_user_logged_in() ) {
			// Let's populate the field with the current users first name
			global $current_user;
			get_currentuserinfo();
			$tag = $current_user->user_firstname; // {YIKES_Example} parsed into the currently logged in users first name
		}
	}
	// return the newly parsed data back to the input field
	return $tag;
}

New Pre Defined Tag on Edit Form page

Parsed Pre Defined Tag on Front End