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because I do.....it's nothing bad or anything...i just do.

Since you have no idea what you are doing, don't bother reinstalling OS X. To change your IP, you can do it in the Network Preferences. However, depending on your network setup , you may not have the luxury of changing your IP address. So before you attempt to solve all your worries so The Man can't find you, you should probably explain your network setup. Are you at home, at school, who's your ISP, are you using a proxy, firewall, or router device...and so on...
 
I enjoy watching people walk down my street with laptop and connect to MY IP address with there laptops.


It pisses me off.
 
IP addresses are typically assigned to you (using DHCP) by some entity outside of your computer, like a router, a corporate network, or your upstream cable/DSL company, so reinstalling the OS has no real bearing on whether your IP address changes.
 
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