As prophesied in the earlier preview for "Neil Patrick Harris' Puppet Dreams" web series, his Dr. Horrible co-star Nathan Fillion stopped by in a doctor's outfit in the newest episode to examine both NPH's puppet problem and his penis. And by penis we mean "the hammer." But of course by "the hammer" we still mean "penis."

Warning: Video contains graphic trouser weasel action. You've been warned.

[Via Nerd Bastards]