[rm -rf /]

I don't know. If you're enough of a geek to be running Linux on a regular basis then you probably know the "rm" command and would be smart enough not to run it and not to randomly run people's usernames from the command lines (although I'm fairly sure "andreboos" is safe).

As for sandwiches, you should already have one.

$ make sandwich
make: Nothing to be done for `sandwich'

(Is that an "interesting" make artifact, a tip of the hat to XKCD or an old easter egg?).

BTW, I'm not going to try it, but I fairly sure that you can do significant damage without root access, in particular, I think you could end up trashing your home directory. rm -rf is a really dangerous command, especially if you're root but even if you're not. rm is "remove" -r is recursive and -f is force, don't ask any questions. The final argument is the directory you want to apply it to / is the root of your disk. Common newbie error is to run rm -rf on a directory and then notice that . and .. are still there, so then run "rm -rf .." (probably very destructive).