The term "electric" comes from the feeling in the air when the player in question has a chance to make a play. Before it even happens, people start anticipating, murmuring. You can feel electric energy shooting through the crowd! Some people hold their breath, others start yelling, people get on their feet. Some examples:
Third and long and Freeney's in the game. My heart started pounding every time.
McNabb in shotgun
It's an "running" down and Fr Delone is in the backfield
It's fourth down and Marvin (or Floyd) is back to receive. You had to stand up to make sure you could see both sidelines in case (no, when!) he turned the corner.
AET, when ED was on his game
ED in a broken field, although sometimes you were holding your breath for the wrong reasons.
Could be:
TD - He has all the abilities to be that guy. With a good line and a game-breaking receiver, we'd be screaming for HCDFB to throw it every single play or wishing for third and long.
Trishton - A couple more games like the last one, especially more like the straight-arm play, and you'll be feeling it.