"Don't send friend requests to people you don't know"
define: know
1. be aware of through observation, inquiry, or information.
If you can send a friend request, you've already satisfied the requirements of knowing by being aware of that person.
As for the term "friend request", doesn't that imply that you're asking to be friends with someone? Not that you're already friends..
define: request
1. an act of asking politely or formally for something.
Facebook is stupid. :|
Yet another reason to move to Google+. Follow me if you've got it!