This started as a test script while I was learning about bit operations, and it slowly evolved into an obfuscated JAPH. I know it exceeds the traditional "4 line rule", but I thought that it would be fun to limit the digits used to only 0 and 1, given the theme. It was not golfed in any way.

Enjoy!

$_=[[[[{},[]],{0111,'01110111',1000,'11100101'},[[]]],{0001,'01111110'
,0110,'00011010',0100,'011001000011111001111010',0010,'00000100',0011,
'01010101000100000001111110100010101000000000101000110000010001001010'
.'10100',0101,'011100001001010100000001'},[[]]]];%_=%{${${$_}[0]}[1]};
$s=eval{$O=0,$C=0,$t='This is my 100th PM post';sub{$O++,$C=@_?$C:eval
pack('b*',vec(pack('b*',$_{1<<(1<<0<<1)*((1<<0+1<<0)+1<<0)}),$O-1,1<<0
)?$_{1<<0}:$_{1<<(1<<1<<1)-1}).$C.pack('c',vec(pack('b*',$_{1<<((1<<0)
+(1<<1*1<<1)+1<<0)}),($O-1)%((1<<0*1<<1)+1<<0),1<<(1<<0+1<<0)+1)).pack
('b*',vec(pack('b*',$_{1<<((1<<0+1<<0)+(1<<1<<1))}),$O-1,1)?$_{1<<((1+
1<<0)+1)}:$_{1<<0}).vec($t,$O-1,1<<(1<<1<<1)-(1<<0))};};;$o=pack('b*',
$_{((1<<1)**(1<<1)-1)**(1<<1)});for(0..unpack('%b*',$o)-(1<<1)){$c=$_-
(($_-$_%(1<<1<<1))/(1<<1<<0*1<<1)+($_%(1<<1+1<<0)?1:0));;$i=(vec($o,$c
,(1<<1<<0+1<<0))+(vec($o,$c+1,(1<<1<<1))<<(1<<1<<0+1))>>((1<<1<<1<<1>>
1)-$_%(1<<1<<1<<1>>1)-(1<<1<<0+1)*($_%(1<<1<<1>>1<<1)?0:1)));$i+=$i%(1
<<1)?-1:1 if((($_+1)%((1<<1+1<<1)+(1<<1)+(1<<1)))&&!(($_+1)%((1<<1)**(
1<<1)-1))||$_+1==(1<<(1<<1+1<<1>>1))+(((1<<1)+1)<<1));$T=vec(pack('C',
$i),0,(1<<1<<1>>1<<1))+vec(pack('b*',$_{(1+((1<<1)**(1<<1))**((1<<1)**
(1<<1)-1))}),$_,1)*(1<<(1<<(1<<1)))+(1<<((1<<1**1<<1)+1));;print pack(
'c',($T+=$T==(1<<((1<<1+1<<1>>1)+1))?0:(1<<(((1<<1+1<<1)>>1)+(1<<0*1<<
1))))-=$_%(1+(((1<<1+1<<1)>>1)+(1<<0*1<<1)<<1))==0?(1<<(((1<<1*1<<1<<1
)+(1<<1<<1>>1))>>1)):0);&$s}print pack('c',$s->(1<<0)^unpack('c',(pack
('b*',$_{(1<<1*1<<1*1<<1)*((1<<1)**(1<<0<<1)-1)**(1<<1<<1>>1<<0)}))));
[download]

bobf

Hint: the bit shifts are fun, but they aren't the main point of the obfuscation.

Tested on

• perl 5.005_03 built for i386-linux (little endian)
• perl 5.6.0 built for sun4-solaris (big endian)
• perl 5.6.1 built for MSWin32-x86-multi-thread (little endian)
• perl 5.8.0 built for i386-linux-thread-multi (little endian)
• perl 5.8.3 built for i686-linux (little endian)
• perl 5.8.4 built for i386-linux-thread-multi (little endian)