Short for Fuck Off And Die, used quite often in the direction of a luser when he/she screws up months of hard sysadmin work.

An example (from Abigail, posted on alt.sysadmin.recovery): "Some luser was given root so he could install some things on a Solaris machine. Luser sees that / only has 60Mb free space. Luser sees that /var doesn't have it's own partition, but there's a partition /local. Luser thinks "must fix!". Luser issues "mv /usr /local". Luser is disappointed I tell him to FOAD and that he should try to salvage with what's available in /sbin, and if not, I've a CD for him he can use to reinstall the OS.