Thin privilege is never knowing that look of relief that washes over a guy’s face when he finds out that you’re married/engaged/in a relationship/gay and therefore aren’t interested in him.
When I was a single fat female, conversations with men were always awkward because most of them spent the entire conversation trying to communicate non-verbally that they never ever want to have sex with me. (Not that I was particularly interested in them either. I just have a lot of male friends.)
After I got engaged, I was amazed at how much more open and friendly men were to me, because they knew I wasn’t trying to hit on them, so it was okay to be friendly back without worrying about coming up with an excuse for why they weren’t attracted to me.
I guess this is one corollary to the whole “friendzone” concept. Not only do certain men get affronted when a woman they consider “attractive” wants to “only be friends”, but they also get nervous when a woman they don’t consider “attractive” shows an interest in friendship.