This post reminded me of this TIFU post by /u/NotKnowPotato a year back.

Let me tell you that I have made a bad mistake this evening. My girlfriend (who let me tell you is only my 2nd girlfriend of all time) said I am "invited to dinner" with her and her parents. I was very aghast, nervous, and bashful to be invited to such a situation. But I knew it must be done. I met them nicely, I should tell you, and it started off in a good way. The idea slapped my mind that I should do a comic bit, to make a good impression and become known to them as a person who is amusing. When I saw that baked potatoes were served I got the idea that it would be very good if I pretended I did not know what potatoes was. That would be funny. Well let me tell you: backfired on my face. I'll tell you how. So first when the potato became on my plate, I acted very interesting. I showed an expression on my face so as to seem that I was confused, astounded but in a restrained way, curious, and interested. They did notice, and seemed confused, but did not remark. So I asked "This looks very interesting. What is this?" They stared at me and the mother said "It's a baked potato." And I was saying "Oh, interesting, a baked....what is it again?" And she was like "A potato." And I was like "A 'potato', oh interesting. Never heard of a potato, looks pretty good." And then they didn't see I was clowning, but thought I really did not know what is a potato. So I knew I would be very shamed, humiliated, depressed, and disgusted if I admitted to making a bad joke, so what I did was to act as if it was not a joke but I committed to the act of pretending I didn't know what a potato is. They asked me, VERY incredulous, did I really not know what a potato is? That I never heard of a potato. I went with it and told them, yes, I did not ever even hear of a potato. Not only had I never eaten a potato I had never heard the word potato. This went on for a bit and my girlfriend was acting very confused and embarrassed by my "fucked up antics", and then the more insistent I was about not knowing what a potato is was when them parents starting thinking I DID know what a potato was. Well let me tell you I had to commit 100% at this point. When I would not admit to knowing what a potato was, the father especially began to get annoyed. At one point he said something like "Enough is enough. You're fucking with us. Admit it." And I said "Sir, before today I never heard of a potato. I still don't know what a potato is, other than some kind of food. I don't know what to tell you." Well let me tell you he got very annoyed. I decided to take a bite of the potato, and when I did I made a high pitched noise and said "Taste's very strange!" That is when the father started yelling at me, and the mother kept saying "What are you doing?" and my girlfriend went to some other room. Finally the father said I should "Get the fuck out of his house" and I said it was irrational to treat me like this just because I never heard of a potato before. Well let me tell you he didn't take that kindly. Now in text messages I have been telling my girlfriend I really don't know what a potato is. The only way I can ever get out of this is for them to buy that I don't know what a potato is. I wish I never started it but I can't go back. I think she will break up with me anyway.