electrical, junction box
A short is not when they spark. When you play with them, and they short, that means that you have a open, and the arcing is also burning the edge of the wire, which in turns causes other problems, due to the voltage spike. If you do not have a good connection, then yes you are going to have sparking from it.
Just to let you know, a Short causes breakers & fuses to trip, and happens when you connect opposite ends (ie white & black, or Black & ground) directly together, without any device between them. In other words, you wire nut the two leads of opposite colors, you have caused a short, and the breaker will not reset to allow operation.