I spoiled myself a little, but was too dumb to get the meaning, and I'm glad that I was dumb. I read in the Wiki of Ice and Fire that Robb was "briefly" married with Jeyne, and thought "well, little Jeyne is going to die". When Robb set off for the wedding I thought that Riverrun would be attacked and Jeyne killed. I also heard the words "Red Wedding" and thought they referred to Joffrey's marriage. As for the actual reading, I was so dumb that I only realized that something was going on when "Rains of Castamere" started playing. I was thrilled and shocked. Even more so in the next chapter when Sandor hits Arya's neck with the axe. I thought Arya was dead too, and was astonished. Later I read Jon's battle at the Wall thinking "Jon is gonna die too, please don't let this happen, he is gonna die, there are so many wildlings and so few watchers, Jon wil die too". The tension was even greater than at the Red Wedding itself.