Halloween Costume searching

According to official googleblog I have just know that Halloween costume search ranking goes very high within this week. Although searches for halloween costume ideas have been growing hot since last august. I never ever attend any Halloween function. So failed to understand what kind of joyful cheerful custom it is on western countries. Look at the keywords on search query below.

2010 halloween costumes [breakout]
snooki costume [breakout]
avatar costume [+800%]
iron man costume [+200%
lady gaga costume [+150%]
mad hatter costume [+70%]
costume express [+60%]
womens halloween costume [+60%]
peacock costume [+50%]
wonder woman [+50%]

Can you tell me what is the meaning of "Avatar Costume"? I am thinking about a costume but...

The percentage shows that how much those words are favorite and the interest growing fast since the start of 2010.

When I read the article on Googleblog. I understand the lackness of my knowledge.
Actually this is not my fault.

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