btw, this would work with slightly older rm from GNU coreutils:
rm -rf --n /
any GNU long option (getopt_long) for any command can be shortened as much as there isn't any ambiguity. And hence the above (this is fixed in latest GNU coreutils release).
Anyone who would compile and run random code from the internet without thinking about whether it's subtly malicious (let alone overtly destructive) has a lesson to be learned that's probably worth the data on their hard drive. If they don't have backups, that's two lessons.
Using this type of code to show unintended consequences is itself a hotbed of unintended consequences!
Just put in code that prints "pwned" instead of running code that would delete someone's system or home folder.