Does there exist a poem that uses direction to change its meaning?

Question

I've been reading about writing order and the question has been poking at me for a while now: since writing order could theoretically introduce ambiguity, is it possible that someone has written a poem that reads differently depending on the direction it's read in?

For example, read left-to-right, it would mean one thing, while read top-down, it would mean something entirely different.

~` ~` ~` ~` ~` ~` ~`
+- +- +- +- +- +- +-
=_ =_ =_ =_ =_ =_ =_

In this pretend language that's supposed to represent Japanese, the poem would read:

~` ~` ~` ~` ~` ~` ~` +- +- +- +- +- +- +- =_ =_ =_ =_ =_ =_ =_
A frog jumped into a pot of boiling water and jumped back out.

or top-down:

~` +- =_ ~` +- =_ ~` +- =_ ~` +- =_ ~` +- =_ ~` +- =_ ~` +- =_
A man went to the deli to buy some ham.

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Edit:

Someone provided an interesting example (now deleted), so I thought I should add this in, since it's probably the reason they deleted their answer:

[addendum] I'm thinking about an example that reads in both directions in full, rather than being "Bible code" or the peppering of a message within a larger text. I did not have the following in mind:

In a small town, there liveD a man who, despIte his lOw inTellect, was loved 
by many. He was an...

Or

I apologize for my rudeness, but I don't quite think YOU know what 
you ARE talking about. Stupidity comes in many forms, not just A poorly 
developed intellect. This common assumption tends to JERK those in the know. 

Rather, something like

I   l i k e   f o o d
n   i c i v   o n n i
    m a l e   r l o n
a   b r l r   g y m n
    o u e y   e   o e
s   , s d o   t k p r
t     ,   n   f n o 
a   t   a e   u o t
g   h v l     l w o
n   e i l     , s e
a     o           i
n   m l o     h a a
t   a e f     e b "
    n n         o ,
    , t         u
      l         t h
      y           e
                "
                  h
                  a
                  d

Pretending for the moment that the vertical passage makes any sense and that "n iciv onni", etc, are English words. Think "crossword puzzle"

Answer 1

One example of a block of text which is fully understandable both vertically and horizontally, is from this comedy. (And I'm afraid I know nothing more complex or sophisticated than this.)

極秘情報 (Top Secret) performed by アンジャッシュ
https://youtu.be/n5JfsbM89v8

ワタシ
カツラ
ナノダ
シカモ
ゲイ○

"モ○" at the bottom right is actually a kanji number 一七〇 (170) written vertically, and "一七" looks like katakana モ.

When read vertically, "シラダ" (whose height is 170cm), "タツノ カイ" and "ワカナ シゲ" are three typical Japanese names.

When read horizontally, it reads "私カツラなのだ　しかもゲイ。" (I wear a wig, and furthermore, I'm gay).

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"Bible Code" type wordplay is much more common, and it probably exists from ancient times. Some people believe that いろは歌, which was created as early as the 10th or 11th century, has such a code.

Today this kind of wordplay is called 縦読み, and you can find new 縦読み created every day in forums like 2ちゃんねる. Recently newspapers often have wonderful 縦読み in TV guide pages.