It's nothing to celebrate. They won one battle, then immediately got their asses handed to them. They don't care about it. They have no reason to.
http://en.wikipedia.org/wiki/Cinco_de_mayo Basically, the US celebrates it more than any Mexican does. Any Mexican that knows their history wouldn't care about Cinco de Mayo. Like my mother, no one in her family cared about it. XD
speaking of cinco de mayo http://kh13.com/forum/statuses/user/22568-koko/?status_id=115558 warning! the preceding link contains so much concentrated cringe you may spontaneously die