Lightswitch zapping me
Most likely static electric discharge as Harper says.  The switch is grounded.  The computer case is grounded.  Walking around on carpet in the winter is a great way to build up a static charge.  When touching some metal at a lower charge a spark will occur.  

The wall switch is at 120V in the US.  A static electric discharge can be 20,000V.  

"... zaps every time it is touched"  Have one person touch it 10 times in 10 seconds.  Only the initial shock and nothing the other 9 times means it is static discharge.  A second person touches it and they got shocked the first time.