The Brazilian, American, and British teams are the only ones I generally get excited about (and even then, only if other people around me are excited about them first).
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Wait a minute, you meant American Football. Never mind then; I'm not particularly a fan. I like playing all sorts of sports, but there are very few I have any desire to watch. Hockey, swimming, and gymnastics tend to be about it (though as mentioned, if I'm around soccer fans, then soccer is quite fun to watch).