split m indigo, reverse for tsujdnrehtonadnlrepdnrekcah; print pop _, 
+pack uc for map a1, times
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(Btw I'm a bit affraid of the message you get when you run it with warnings:

Unquoted string "tsujdnrehtonadnlrepdnrekcah" may clash with future reserved word

what if someone convinces p5p to add a tsujdnrehtonadnlrepdnrekcah core function to perl 5.10, just to break this japh.)

Update 2006 Jun 27: a related but simpler japh is this:

s no unpack uc uxanexg and print for lc reverse rekcahuolrepuorehtonau
+otsuj
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btw, the digit 1 is not needed in the original japh but I won't remove it now.

Update 2012-10-09: as mentioned in Bitrotten obfuscations, the first obfu no longer works as is since perl 5.12, so as a fix, prepend @_= like this:

@_= split m indigo, reverse for tsujdnrehtonadnlrepdnrekcah; print pop
+ _, pack uc for map a1, times
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Even after this fix, you get a default warning thoguh.