A guy who always gets in the way of two girlfriends hanging out.

Most likely it is one of the girl's boyfriends who makes plans to hang out with her during all her spare time, leaving no time for the best friend to see her.
Girl 1: Hey do you want to hang out on Saturday?
Girl 2: Sorry, my boyfriend already asked me.
Girl 1: Again? Uhgg he's such as BFF Blocker!

Example 2:
Girl 1: So, girl's night out! What are we going to do?
Girl 2: Actually, my boyfriend wanted to come too. Hopefully that's okay!
Girl 1: Didn't you just hang out with him all day? We need BFF time! He's being a BFF Blocker.
by loldawgs February 1, 2011
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