Probably follows the same rule as pluralizing "penis". [He doesn't even crack a smile, but...was that a joke? Did he just reference the joke about pluralizing "penis", or is he serious?]

[If anything, he looks a bit more sour for a moment] Need to train you better, kid. "Horrible stuff" can happen at any time. You gotta be ready.

...But I like techno, hip hop, and some trance. Just for the record.