Some Zodiac researchers have explored the possibility the Zodiac was of English origin, on account of his word usage, such as 'shall', infrequently used in American English, but by the same token a word frequently used by thespians. Peek-a-boo
is known as Peep-bo in British culture and is the act of concealing ones face behind the hands or other object, before suddenly appearing back into view and uttering the words peek-a-boo or peep-bo. It can be seen in Wikipedia that many variations involve trees, similar to the depiction on the Halloween Card, where 'Hiding behind that tree' is added. See here.
Whether or not it is a significant phrase by the Zodiac Killer is open to question, but Peep-Bo is a character that features during Act I of the Mikado.
The eyes peering from the tree, peek-a-boo and the hidden gender, may just have been the start of a form of 'toilet humor' backlash or closet acceptance that the Paul Avery reference to Zodiac possibly being a 'latent homosexual' had been officially noted. After all 'lav' is a colloquialism used in English speech for lavatory or 'water closet'. A 'closet homosexual' is used for people who have not disclosed their sexual orientation or gender identity and ties in nicely with the English phrase 'skeleton in the closet', coined in the 19th century, a colloquial phrase and idiom used to describe an undisclosed fact about someone which, if revealed, would have a negative impact on perceptions of the person. Falling back to the theatrical connection and the Mikado, 'Skeleton in the Closet' was a 1965 Japanese 'Pink Film', also called 'Secrets Behind the Wall'. A 'Pink Film' deals with Japanese theatrical films of nudity, almost exclusively shot on 35mm film, but in order to circumvent censorship restrictions Japanese directors carefully positioned props over the actors private parts, although one doubts a pumpkin found its way on to set very often. Incidentally pumpkin seeds have long been used in parts of Asia for boosting sexual performance and prostate health.
Thank you." The card used was a Jolly Roger greetings card.and we know that a Jolly Roger is a traditional English name used to refer to the flag depicting part of a skeleton and displayed on pirate ships. The links are there but are they interconnected. Was the Halloween Card a form of base subtle humor, along with the Dragon Card that implied the Zodiac Killer did indeed harbor a deep felt resentment against not only against Paul Avery and the San Francisco Chronicle, but also the police in general, not only for the reasons we have become accustomed to, but for reasons far more personal to our killer, leaving us to wonder if the 'skeletons in the closet' may have been rattled loose just slightly and the 'mask' of the Zodiac Killer may one day fall to reveal his true identity.