What is a sense of humour? The Macmillan English Dictionary simply says a sense of humour is 'the ability to laugh at things or say funny things'. Now, the tricky part is different people find different things funny.
Sometimes this can lead to embarrassing situation or even conflict. An individual may say something with the intention of being funny and the listener is not amused. Not only do they not think it is funny but they could be offended.
Why don't all people find the same things funny? Culture will have an influence on humour. There are things many brought up in a particular culture will find humorous, but people from other cultures won't get it.
I love a good Aussie comedy but there will be jokes someone living in another country won't understand.
Age and socio-economic standing influence your sense of humour. Sometimes 'the younger generation' won't get a joke that makes reference to an event of decades ago or something that used to be commonplace in most homes back in the fifties or whenever.
Things people find funny now are often different from what amused people in the past. Shows I found hilarious when we first got television back in 1963 would probably seem corny to me now. Part of that is because I was a child then and part is because humour has changed.
Individual life experiences will influence a person's sense of humour. A couple or family may have jokes no one else understands. Or they will burst out laughing really loudly when others find the joke only mildly amusing.
There may be jokes from a particular movie or TV series which continue to amuse those who watched it together. These shared jokes strengthen the bond between the individuals.
One of the great things about humour is how it helps people get through some experiences in life which are anything but funny. Amy Tan, writer of The Joy Luck Club says, '... what makes people resilient is the ability to find humour and irony in situations that would otherwise overpower you.'