above: Arnold Horshack
In spite of their similar-sounding names, these characters are very different.
Rorschach is a vicious vigilante from the comic book (and now movie) The Watchmen.
Arnold Horshack is a character from the 70s situation comedy Welcome Back Kotter, known for saying "Oo oo ooo" when he raised his hand (pictured).
Not to be confused, indeed.