It takes more energy to be an asshole than it does to be nice. And when you act like a dick you end up feeling like one.
When you are nice (better yet – funny and nice), you make everyone feel better, including yourself. As a bonus, you immediately become more attractive to those around you, which has its own benefits.
And whoever you were nice to is now predisposed to act the same way to the next person they meet. See how easy it is to make the world a better place?