[!MaxiGallery? &display=`childgalleries` &childgalleries_ids=`38` &limit=`1` &order_by=`random` &childgalleries_level_limit=`3` &manageButtonTpl=`CODE:`!]
[!MaxiGallery? &childgalleries_ids=`38` &display=`childgalleries` &childgalleries_limit=`1` &manageButtonTpl=`CODE:` &manageOuterTpl=`CODE:` &galleryOuterTpl=`outerrandomportfolio` &childgalleryTpl=`gallerylisting`!]

[!MaxiGallery? &childgalleries_ids=`38` &display=`childgalleries` &order_by=`random` &childgalleries_limit=`1` &manageButtonTpl=`CODE:` &manageOuterTpl=`CODE:` &galleryOuterTpl=`outerrandomportfolio` &childgalleryTpl=`gallerylisting`!]
[+maxigallery.childgalleries+]
<a href="[+maxigallery.childurl+]"><img src="[*myimage:phpthumb=`h=130&w=130&zc=1#[+maxigallery.path_to_gal+][+maxigallery.picture.filename+]#1`*]" class="brdrdashed" title="[+maxigallery.strings.go_to_gallery+]" alt="[+maxigallery.strings.go_to_gallery+]" /></a><br /><b>Client:</b> [+maxigallery.pageinfo.pagetitle:htmlent+]

Hmm.. Are you sure that you are reading the correct wiki page?
Try: &childgalleries_order_by=`random`
[!MaxiGallery? &childgalleries_ids=`38` &display=`childgalleries` &childgalleries_limit=`1` &childgalleries_order_by=`random` &manageButtonTpl=`CODE:` &manageOuterTpl=`CODE:` &galleryOuterTpl=`outerrandomportfolio` &childgalleryTpl=`gallerylisting`!]
//if random order, use mysql RAND()
if ($sortby == "random") {
$order = "RAND()";
}else{
$order = $sortby;
}
$resources = $modx->getDocuments($kids, $showPublishedOnly, 0, "*", '', $order, $sortdir);
//if random order, use menuindex for the sql query
if ($sortby == "random") {
$order = "menuindex";
}else{
$order = $sortby;
}
$resources = $modx->getDocuments($kids, $showPublishedOnly, 0, "*", '', $order, $sortdir);
//if random order, shuffle the resources array
if ($sortby == "random") {
shuffle($resources);
}
if ($limit != 0) {
$resources = array_slice($resources, 0, $limit);
}
$resources = shuffle($resources);
shuffle($resources);