Request for Startups: http://ycombinator.com/rfs.html

It stands for Request for Startups, which is a wink and nod (reference) to documents that describe internet standards, which are called RFC. For example, the document that lays out the HTTP protocol is RFC2616 https://tools.ietf.org/html/rfc2616

What does RFC stand for? "Request for Comments". Presumably, because standards have to be reviewed by other people and get their feedback.

I assume the spirit is same here.

Nope. I had to search the internet, article and finally this thread, trying to find out what it meant.

As far as I can tell, the other answer on your comment seem to be the only place on the internet where this usage of this acronym is documented.