// URL http://www.domain.com/?colors[]=Red&colors[]=Blue&colors[]=Green&colors[]=Yellow&animals[]=Fish&animals[]=Dogs

parse_str($_SERVER['QUERY_STRING'], $values);
foreach($values['animals'] as $animal) {
	foreach($values['colors'] as $color) {
		echo "This page is about selling " . $color . " " . $animal . PHP_EOL;
	}
}