if it's rc2
files to edit \templates\base\scripts
BxBaseIndex.php
around line 322
// top menu and sorting
$aModes = array('last', 'top', 'online');
$aDBTopMenu = array();
change to
// top menu and sorting
$aModes = array('last', 'top', 'rand', 'online');
$aDBTopMenu = array();
around line 337
case 'last':
if ($sMode == $sMyMode)
$sqlOrder = " ORDER BY `Profiles`.`Couple` ASC, `Profiles`.`DateReg` DESC";
$sModeTitle = _t('_Latest');
break;
just below add
case 'rand':
if ($sMode == $sMyMode)
$sqlOrder = " ORDER BY `Profiles`.`Couple` ASC, RAND()";
$sModeTitle = _t('_Random');
break;
that's it :)