Electrical Work

I am not an electrician but have done some small jobs around the house like outlets and switches. Recently we were at Scott and Jenna's house and they needed a different receptacle for their dryer. Scott flipped the breaker and away we went, starting to change the device. That is when I sensed a burning in my thumb that was touching a couple screws. I pulled away rather quickly, just before screaming. Just kidding about the scream but it did burn a bit. The problem was found to be that someone had attached a wire to two separate breakers. We did get a new breaker put in so everything is working properly.