A simple function for mimicking drawing names from a hat.

draw-names.php

<?php

function draw_names_from_hat( $names =  array(), $couples = false ) {
	$hat = $names;
	
	foreach ( $names as $key => $name ) {
		$pick = array_rand( $hat );
		
		if ( $name == $hat[$pick] ) {
			unset( $hat[$pick] );
			
			$pick = array_rand( $hat );
			
			array_push( $hat, $name );
		}
		
		if ( $couples == true ) {
			if ( $key % 2 == 0 && $key + 1 == $pick ) {
				$paper = $hat[$pick];
				
				unset( $hat[$pick] );
				
				$pick = array_rand( $hat );
				
				array_push( $hat, $paper );
			}
			
			if ( $key % 2 == 1 && $key - 1 == $pick ) {
				$paper = $hat[$pick];
				
				unset( $hat[$pick] );
				
				$pick = array_rand( $hat );
				
				array_push( $hat, $paper );
			}
		}
		
		$paired[$name] = $hat[$pick];
		
		unset( $hat[$pick] );
	}
	
	foreach ( $paired as $name => $pick ) {
		echo $name . ' = ' . $pick . '<br/>';
	}
}