Relatable-means a connection to relate events to probable causes. It is more about performance: how the performance was able to connect to the audience. Relevant-means closely connected to the current situation. It is more about content or material that is meaningful in the present. So the guy that said "shut up" said it was not relatable because the audience would not be able to relate to it or understand about having a farm since they don't own a farm. Hope that makes sense! ^^

Hmmm....the word does not make sense to me in that context. In fact, I don't believe I have ever heard the word used. It is a word and means the same as related, relevant, applicable. However, it sounds unnatural in the sentence you gave. I googled the two words and their usage is similar but somewhat different. Again, relatable is not a commonly used word. In fact, my computer's spell check does not even recognize relatable.