Laughter

Children will laugh at the simplest things.  Something little will just set them off - a silly noise, a crinkle of your nose, a wiggle of your fingers.  Once set off it becomes easier and easier to bring the giggles to the surface.  Even the most determined adult will eventually brake into a smile and maybe even a little laugh too as their actions continue to bring hysterics to the little faces.  Somehow those little things that weren't funny at all to begin with are hilarious and you just can't stop laughing either.  

Here's a little bit on how laughter is good for you...

1.) Increase your antibody producing cells -> strong immune system -> help to fight infection

2.) Emotional release

3.) Connecting with other people -> build stronger relationships

4.) Better blood flow

5.) Relaxation 

{my sources: about.com & webMD}