It will eventually show whom it is (or whom they are).
If it's just one guy, it's probably someone you've been having a dialog with in a thread.
It still could be spam: some guys just go down a thread and hit add on every person. Multiple posts to a thread could get you multiple requests. Some people are that desperate others think they'll get points.
AFU stands for
or is an acronym for
American Civil Liberties Union
It's not a "no-name" member.
The site is AFU. Sometimes member names do not show.
You may get PMs from blank names and have gaps in your friends list.
Also, you may notice names disappearing from PMs you haven't deleted yet that had names yesterday.
I've been suffering from this condition for a month now. 7 support emails, 6 PMs to Mods & 2 posts in the support section all have gone unanswered. AFU (Thanks SoyBob)