When is a joke no longer funny?

I think there are two types of humour: the humour that is at the expense of others and the humour that includes others. When you don't mind picking on people then you will find the humour which is at the expense of others funny. Jesus often made fun of religious people because he thought that what they stood for was a joke. But what happens when you pick on 'the little guy.' Over the last two weeks we have seen The Chaster pick on dying kids and Gordon Ramsay pick on Tracy Grimshaw. I love having a good laugh but when you pick on the 'little guy' it ends up just not being funny.