The reason behind it is
*When you are sad or angry,it's good to laugh loud,because if your sad,the pulses are generated in brain and these pulses are generated through our nerves and disturbs the function of our body.So if you laugh loudly
the ear hears it and the pulses are generated and the brain will sense that you are happy,it convinces your brain that you are happy.Thats why Thiruvalluvar said"LAUGH UNDER TOUGH SITUATIONS"
2.You can see any faces/Objects in your dream,except your face and mirror(which reflects your face).
