[[PeopleGroups? &user=`11` &limit=`0`]]
[[PeopleGroups? &user=`[[!+modx.user.id]]` &limit=`0`]]
This question has been answered by Bruno17. See the first response.
<?php $user = $modx->getOption('user', $scriptProperties, 0); return $user;
[[!PeopleGroups? &user=`[[!+modx.user.id]]` &limit=`0`]]