It's perfectly fine to be Packers fan, but I would judge a person who showed up to a wedding or funeral dressed as a cheesehead.
Nitpick on wording: I wouldn't call wearing a suit to a wedding “looking like a non-Packers fan” -- it's not like non-Packers fans are all that much more likely to do so than Packers fan; I'd call it “not looking like a Packers fan”. By the same token, on hearing “looking like a non-nerd”, I think about an appearance that's significant evidence than you're not a nerd; I'd refer to an appearance that doesn't provide much evidence one way or another as “not looking like a nerd”.
This is a repository for major, life-altering mistakes that you or others have made. Detailed accounts of specific mistakes are welcome, and so are mentions of general classes of mistakes that people often make. If similar repositories already exist (inside or outside of LW), links are greatly appreciated.
The purpose of this repository is to collect information about serious misjudgements and mistakes in order to help people avoid similar mistakes. (I am posting this repository because I'm trying to conduct a premortem on my life and figure out what catastrophic risks may screw me over in the near or far future.)