$re = '/^.*?(?=\s+[^:\s]+:)|([^:\s]+):([^:\s]+)/';
$str = 'test text user:testuser,anotheruser hashtag:peach,phone,milk site:youtube.com,twitter.com flair:😂bobby😂';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php