word substituition?

I am looking for a simple way to substituite words in a php echo...
For example I would like to create a sentence but alter choice words at random ( or maybe conditional ) within the sentence.

For example I had a sentence...

[ Fred | Jane | Paco ] likes the color [ purple | red | green ] best of all.

What I am wanting is to get a random result each time...

Any ideas?

 

<?
	$mystring = "the shape is color";
	$color = array("red","yellow","green","blue","orange","purple","cyan");
	$shape = array("square","circle","rectangle","oval","triangle","hexagon","octagon");
	
	$mystring = preg_replace("/shape/i",$shape[mt_rand(0,count($shape)-1)],$mystring);
	$mystring = preg_replace("/color/i",$color[mt_rand(0,count($color)-1)],$mystring);

	echo $mystring;
?>

PHP:

 

<?php
$names = array_flip(array("Fred", "Jane", "Paco"));
$colors = array_flip(array("purple", "red", "green"));
echo array_rand($names) . " likes the color " . array_rand($colors) . " best of all.";
?>

PHP:

EDIT:: Not sure if it's the best way to go about things, but it works.

 

<?
function random_sentence_from_arrays( $format, $first, $second, $third )
{
	return sprintf(
		is_array( $format ) ? $format[ array_rand( $format ) ] : $format,
		$first[ array_rand( $first ) ],
		$second[ array_rand( $second ) ],
		$third[ array_rand( $third ) ]
	);	
}

$names = array(
	'Joe',
	'livingearth',
	'ansi',
	'NinjaNoodles'
);
$shapes = array(
	'square',
	'circle',
	'triangle',
	'oblong',
	'elephant'
);
$colors = array(
	'red',
	'orange',
	'blue',
	'green',
	'pink',
	'violet'
);
$formats = array(
	'%s once bought a %s %s for a gajillion dollars',
	'%s is of the opinion that %ss always look best on a %s',
	'In some countries guys named %s get shot if they do not carry thier %s socks in a %s box',
	'Q: What is %s\'s favourite color ?? A: %s'
);
for( $i = 0 ; $i < 10 ; $i ++ )
{
	printf( "%s<br />", random_sentence_from_arrays( $formats, $names, $colors, $shapes ) );
}
?>

PHP:

The most random I can be .....