$re = '/(?<=\s)(ich|ja|das|für|und|nein|doch|bock|kopf|lust|schnell|weg|zug|frei|bald|echt|klar|laut|nass|süß|toll|witz|ziel|haar|haus|wort|zeit|schatz|funk|glück|kuss|maus|nacht|paar|rund|satz|tage|ufer|viel|wald|welt|zahn|zelt|bunt|dorf)(?=\s)/m';
$str = 'How many of you have a Colin Robinson in your life? Someone who drags out conversations for as long as they can after you say,
"I gotta go, dude." Someone who asks you for favors they never return. Someone who will talk so fast in rambling sentences that you can\'t get in a word edgewise when you are just talking to them.
An energy vampire? I think I finally got rid of my Colin Robinson today! (Image)
Quand tu es chauve, qu\'il fait-5°c, et que tu as oublié ton bonnet. #memecredi (Image)
';
preg_match_all($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