Nice formatting. Here's a few comments :-)

# basic structure defines and calls the sub like so:
# &{sub{print shift;}}('Just Another Perl Hacker')

&{sub{
@_=split (/ /, shift);          # @_ = (peek, it, please)
print reverse split(//,shift);  # shift gets @_[0] -> 'peek' so prints
+ 'keep'
print' ', shift, ' ';           # shift gets @_[0], now -> 'it; prints
+ ' it ';
@_=split ( //, shift);          # splits please @_ = (p,l,e,a,s,e);
push @_,                        # pushing array of strings into @_
shift().                        # 'p' from @_ , () supress warning
shift,                          # 'l'
chr(ord(shift)+8).              # 'e' + 8 -> fghijkl -> 'm'
chr(ord(shift)+8).              # 'a' + 8 -> bcdefgh -> 'i'
shift,                          # 's'
shift;                          # 'e'
                                # @_ = (pl,mis,e)
print reverse split ( //, splice(@_,1,1)); # slurps mis -> 'sim'
print @_;                       # @_ = (pl,e)
}}   
('peek it please');             # arg
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tachyon