My son was badly shocked today plugging in cable
Sometimes TV's can, & do build up HUGE static charges on them, and if the area is dry, and there is carpet on the floor huge sparks of static electricity will arc out from TV, this is frightening, but relatively harmless, and happens infrequently, it happens due to the TV being at one potential, and the "Son" as another, charge is generated by walking across the carpet, and in TV it;s just a product of being "ON" When conditions are exactly right.... Zap.... touching any "Grounded" thing before approaching a TV is always a good idea. I have seen this and experienced this myself on a number of occasions, not always with TV's too. I assume it was static, due to the fact that you weren't also telling us your son was dead...If one got a huge arc and shock,from the mains, they seldom live to tell the tail. But static, just nips you, and you have a good story to tell.
Now of course thats assuming that, that is what it was, in any event, please ensure you check over all cables for any damage or bare wires, replace if even slightest defect.