Speed Bumps – Example code to accompany http://fus.in/1MidK1N

second-functions-sample.php

<?php
add_filter( 'speed_bumps_rickroll_constraints', 'give_you_up', 10, 4 );

function give_you_up( $can_insert, $context, $args, $already_inserted ) {
	if ( ! preg_match( '/give [^ ]+ up/i', $context['prev_paragraph'] ) ) {
		$can_insert = false;
	}
	return $can_insert;
}