<p>Is there a way in FreeBSD to (being root) run a command as unprivileged user, like nobody? Kind of like reverse of sudo. Oh and considering that 'nobody' has /usr/sbin/nologin as shell - so <b>su</b> is not an option.</p>

sudo will allow you to run a command as another user.
```
```
sudo -u nobody <command>
```
```
will run  as nobody, even if their login shell is not available.