How to be funny ....?

I have a lot of people that are funny and I just don't seem to be one. Like one time my friend and me were watching ripley's believe or not. And theres a fat lady and she got stuck somewhere and they saved her. And then the lady on the tv said "I have not loss my sense of humor". Then my friend says "neither has your weight". i would have never thought of that. how do you do it?