Fair enough... Your first obfuscation, and my first crack at working one out....

SPOILER:
First $_ is set to a confusing looking string with lots of brackets & stuff in it.
Next the regex y is used with the d modifier. (It's an alias for tr) This converts all of the weird looking characters to legal hex code characters.
d deletes all characters found in SEARCHLIST that do not have a corresponding character in REPLACEMENTLIST
Then $h is set to "H8" which will be used as a parameter for pack, telling it to use Hexidecial with high nybble first.
pack is then called (why didn't you just omit $h altogether & write  $_=pack("H8",$_) ???)
This produces a 4 letter string which is translated (this time actually using tr) to "JAPH"
Then a newline is tacked onto the end & the result is printed.

What makes this obfuscation work is the use of escaped delimiter characters in the Regular Expressions, they make it difficult to follow. 8-P
It kind of reminds me of the solitare encryption proggy written in the Neal Stepenson Book, Cryptonomicon.


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Wait! This isn't a Parachute, it's a Backpack!!!