Aristotle wrote, As for Comedy, it is an imitation of men worse than the average; worse, however, not as regards any and every sort of fault, but only as regards one particular kind, the Ridiculous, which is a species of the Ugly. (Poetics, 1449a, Ch. 5). In a crude sense, I suppose he means we laugh at the pitiful; it's the so called schadenfreude. That we derive amusement by seeing others suffer, as it makes us feel better about our own miseries and inadequacies. I've been guilty of it and this kind of humour is "sick," but I think Aristotle is right. Should one feel bad because they laugh at the misfortunes of others?