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$this && $that   |    If $this is true, return $that,          
...
$this || $that   |    If $this is true, return $this,
$this or $that   |    else return $that.
---------------------------------------------------------

my ($first, $second) = ( 1, 1 );
print "Truth\n" if $first++ && $second++;
...
Truth
First: 2
Second: 2

my ($first, $second) = ( 1, 0 );
print "Truth\n" if $first++ && $second++;
...
# Note: Both are evaluated because the first one is
# true.  But "Truth" isn't printed, because only one
# of the two expressions evaluated "true".

my ($first, $second) = ( 0, 1 );
print "Truth\n" if $first++ && $second++;
...
Second: 1
# $second didn't get incremented because the
# evaluation stopped when $first evaluated false.

my ($first, $second) = ( 0, 0 );
print "Truth\n" if $first++ && $second++;
...
Second: 0
# $first was evaluated for truth.  It was false,
# so $second didn't get evaluated.

my ($first, $second) = ( 1, 1 );
print "Truth\n" if $first++ || $second++;
...
Second: 1
# Since $first is true, no need to evaluate $second;
# we already know that the 'or' expression is true.

my ($first, $second) = ( 1, 0 );
print "Truth\n" if $first++ || $second++;
...
Second: 0
# Again, $second is never evaluated because $first
# is true, and that's good enough for ||.

my ($first, $second) = ( 0, 1 );
print "Truth\n" if $first++ || $second++;
...
# Both sides got evaluated because since $first was
# false it was necessary to evaluate $second to 
# determine if truth exists (it does).

my ($first, $second) = ( 0, 0 );
print "Truth\n" if $first++ || $second++;
...
Second: 1
# There is no truth.  Both expressions were
# evaluated to find it.

open( FILE, "<filename" ) || die "Cannot open filename: $!\n";
# Open the file.  If the open fails (and thus evaluates 
# false) fall through to the second half: die.

local $_ = 'xyz';
SWITCH: {
...
    /^xyz/ && do { $xyz = 1; last SWITCH; };
    $default = 1;
}

if ( $this && $that && $other ) { print "Truth\n"; }

my $client = $ENV{USER_HOST} ||
             $ENV{USER_ADDR} ||
             "UNKNOWN";

my @sorted = sort { uc($a) cmp uc($b) || $a cmp $b } @unsorted;

my @list = ( { 'Name' => "Pete", 'Age' => 32 },
             { 'Name' => "Pete", 'Age' => 55 } );
my @sorted = sort { $a->{'Name'} cmp $b->{'Name'} ||
                    $a->{'Age' } <=> $b->{'Age' }   } @list;

open ( FILE, "<filename" ) || die ..... # You already saw this one.
open FILE, "<filename" or die .... # Notice how the much lower
# precedence of "or" makes the parenthesis unnecessary in
# this case.