"Harrison, Dr. (John Bellah): Young pathologist who catches the Psi 2000 virus; Spock sees him in a passageway, painting "Love Mankind" and "Sinner Repent" on the bulkheads and laughing hysterically. McCoy later calls Dr. Harrison on the intercom and gets nothing but laughter."
In the TOS episode The Naked Time
, McCoy calls down to the biopsy lab on the intercom, asking for a report, and calls for the guy on the other end (calling out "Harrison"), but gets no answer...
...Later in the episode, McCoy calls the biopsy lab again looking for the report, and the guy at the other end (this time no name given) sounds like he is infected with the "Naked Time Disease" and was babbling and laughing (he actually sounded like he was wasted from smoking a doobie