Why Do You Laugh?

laugh (p)
1. To express certain emotions, especially mirth or delight, by a series of spontaneous, usually unarticulated sounds often accompanied by corresponding facial and bodily movements.
2. To show or feel amusement or good humor
3. To feel or express derision or contempt. To feel a triumphant or exultant sense of well-being.

Give it some thought... we laugh because:
someone else did or said something stupid?
or we are embarassed we never thought of that possibility, thus use the laughter as a cover-up for the embarassment?

Now whenever i start to laugh, i pause and think about what made me laugh. What was said or did that made me feel embarassed? I can learn something from this laughter!