The week before Reign in Blood was released, I was at a record store with a friend and I was looking to buy something new that I'd never heard. At the time, we were mainly into punk and hardcore, and were just hearing some bands that were getting into the crossover scene. I was listening to a lot of Discharge, early Corrosion of Conformity, DRI, Agnostic Front, English Dogs, etc. I had recently picked up SOD Speak English or Die. Anyway, I hadn't even heard of Slayer, but my buddy grabbed the Haunting the Chapel vinyl, and said "you should buy this!"
So, I did. I was an instant Slayer fan. The next weekend, I went down to the record store to see what other Slayer they had. As I am walking in, the record store guy is taking the Reign in Blood records out of a box and putting them on a rack on the wall. I literally grabbed one out of his hand.
Now, as much as I liked Haunting the Chapel, when I got home and listened to RIB, I was absolutely fucking stunned!
It's a classic without question. IMO one of the top 5 metal albums ever made.