I'm certainly not a master of obfuscation, but I figure while I'm learning I might as well hit two languages at once. The below obfuscation "translates" english from STDIN into leetspeek, which is as good as obfuscated...
goto a;STDIN:$f=length($_);package atoi;while(<STDIN>){{@_=(5,2,12,
6,3,7,0,2,13,3,0,2,8,2,7,2,1,6,7,2,0,2,13,3,14,3,0,2,2,2,1,6,12,2,1,
4,12,2,4,3,12,2,4,3,12,2,4,3,12,2,4,3,12,2,0,4,12,2,0,4,2,2,12,2,7,2,
2,6,7,2,0,2,13,3,14,3,0,2,7,2,2,6,12,2,2,4,12,2,8,3,7,2,12,2,7,2,3,6,
7,2,0,2,13,3,14,3,0,2,7,2,3,6,12,2,3,4,12,2,8,2,12,2,11,6,12,2,11,4,
12,2,12,7,12,3,12,2,15,2,12,3,7,2,12,2,7,2,4,6,7,2,0,2,13,3,14,3,0,2,
7,2,4,6,12,2,4,4,12,2,12,7,9,2,7,2,12,2,7,2,5,6,7,2,0,2,13,3,14,3,0,
2,7,2,5,6,12,2,5,4,12,2,3,3,12,2,3,3,12,2,3,3,12,2,3,3,7,2,12,2,7,2,
6,6,7,2,0,2,13,3,14,3,0,2,7,2,6,6,12,2,6,4,12,2,0,7,8,6,12,2,0,5,8,6,
12,2,0,7,8,4,12,2,0,5,8,4,7,2,12,2,7,2,7,6,7,2,0,2,13,3,14,3,0,2,7,2,
7,6,12,2,7,4,12,2,6,3,12,2,6,3,12,2,6,3,12,2,6,3,7,2,12,2,7,2,8,6,7,
2,0,2,13,3,14,3,0,2,7,2,8,6,12,2,8,4,12,2,12,7,13,2,12,7,7,2,12,2,7,
2,9,6,7,2,0,2,13,3,14,3,0,2,7,2,9,6,12,2,9,4,12,2,1,3,7,2,12,2,7,2,
11,6,7,2,0,2,13,3,14,3,0,2,7,2,11,6,12,2,11,4,12,2,3,6,12,2,3,4,12,2,
12,7,12,3,12,2,15,2,12,3,7,2,12,2,7,2,12,6,7,2,0,2,13,3,14,3,0,2,7,2,
12,6,12,2,12,4,12,2,12,7,15,5,7,2,12,2,7,2,13,6,7,2,0,2,13,3,14,3,0,
2,7,2,13,6,12,2,13,4,12,2,12,7,12,5,15,2,12,7,7,2,12,2,7,2,14,6,7,2,
0,2,13,3,14,3,0,2,7,2,14,6,12,2,14,4,12,2,12,7,12,5,12,7,7,2,12,2,7,
2,15,6,7,2,0,2,13,3,14,3,0,2,7,2,15,6,12,2,15,4,12,2,0,3,12,2,0,3,12,
2,0,3,12,2,8,2,9,2,7,2,12,2,7,2,0,7,7,2,0,2,13,3,14,3,0,2,7,2,0,7,12,
2,0,5,12,2,12,7,2,3,7,2,12,2,7,2,1,7,7,2,0,2,13,3,14,3,0,2,7,2,1,7,
12,2,1,5,12,2,11,6,7,7,7,2,12,2,7,2,3,7,7,2,0,2,13,3,14,3,0,2,7,2,3,
7,12,2,3,5,12,2,5,3,12,2,5,3,12,2,5,3,12,2,5,3,12,2,4,2,12,2,4,2,12,
2,4,2,12,2,4,2,12,2,10,7,7,2,12,2,7,2,4,7,7,2,0,2,13,3,14,3,0,2,7,2,
4,7,12,2,4,5,12,2,7,3,12,2,7,3,12,2,7,3,12,2,11,2,12,2,11,2,12,2,11,
2,7,2,12,2,7,2,5,7,7,2,0,2,13,3,14,3,0,2,7,2,5,7,12,2,5,5,12,2,12,7,
15,5,12,7,7,2,12,2,7,2,6,7,7,2,0,2,13,3,14,3,0,2,7,2,6,7,12,2,6,5,12,
2,12,5,15,2,12,2,15,2,7,2,12,2,7,2,7,7,7,2,0,2,13,3,14,3,0,2,7,2,7,7,
12,2,7,5,12,2,12,7,15,2,12,5,12,7,12,2,15,2,15,2,7,2,12,2,7,2,8,7,7,
2,0,2,13,3,14,3,0,2,7,2,8,7,12,2,8,5,12,2,14,3,12,3,12,2,8,7,15,6,2,
7,12,2,8,7,0,3,2,7,7,2,12,2,7,2,9,7,7,2,0,2,13,3,14,3,0,2,7,2,9,7,12,
2,9,5,12,2,12,5,7,2,15,2,7,2,12,2,9,2,11,3,);$l=\@_;local$_="";(join
'',@$l)=~m(331(.));foreach$`(@$l){vec($_,$;++,$+)=$`;}eval()if(!//);
use overload'+'=>\&a;}$:=$_;foreach$l(split("",$:)){goto l;b:$v=($ls
{$l}eq'')?g($l):split(",",$ls{$l})&&print$_[$f+$.];goto t;;;l:$.=(
length($:)>$l)?unpack("s",$:)/4:1;sub new{my$a=shift;bless[@_],$a}sub
a{shift->[0]}$l=~tr/A-Z/a-z/;$f=new atoi(rand(scalar(split(",",$ls{$l
}))));goto b;;;t:print$l^$_[$.]if($;==$+);}}sub g(){print $l;}goto
f;a:print"leetspeek"if(scalar(@_)!=0);;goto STDIN;f:print"";