It is the funny image used as a background on the computer screen, by and large for the desktop of a graphical user interface
As nature and friends gives us a reason to smirk. Anger and antagonism gives us a reason to be cruel.
Similarly, on watching funny wallpapers, it makes us laugh. As proved by research, laughing is as important for a person as air to live happily. There are many moments in our life where we can enjoy and feel the happiness; funny wallpapers help you to keep smiling.
Some of my friends love wallpapers so much that they change it 2-3 times a day. It might be a foolish thing to share but I've noticed wallpapers effect personality. Particularly, for those people who love to write (like me) and are found near the computer almost all the time.
After seven years of marriage, I'm sure of two things -- first, never wallpaper together, and second, you'll need two bathrooms... both for her. The rest is a mystery, but a mystery I love to be involved in.