It's something that spoils you the story/movie/episode/book/etc. For example if you go and see the plot for a book,and then go read the book it wont be that interesting cause you already read the plot of it. It kinda depends on people types. Sometimes when I miss an episode,I go find the plot, and the episode after that is still interesting. I guess it depends on all the stuff :/ Next time if you have a question on what something means,just type the weird word in Google and it will find tonn of meanings to the word. Usually the unknown words are part of Internet slang, and no one knew all the words of the slang right away. I am a part of the internet for 4 years now,I still know very little about it. I hope this helps!