Why do I get the chills? A.k.a "goosebumps"?

I was watching south park the episode where Kenny is sick and he is dying and I don't know its kind of sad lol and when there was a sad scene like when cartmen tells Kenny that he's his bestfriend I got the chills lol.. So I was just wondering why do I get them? I even get them when I'm not doing anything even if I'm just literally sitting on the couch not thinking about anything.. Is it normal to get goosebumps very often?