I don&#x27;t really get how that pun works (it&#x27;s not as though that&#x27;s a common phrase).  It seems more likely that it&#x27;s chosen just because five is a round number.<p>If we&#x27;re just going for homophones it could just as easily be &quot;fifth floor&quot; but that also doesn&#x27;t make a lot of sense as a pun.