If you're talking about Parental Controls blocking you from certain apps, no way to do it without the passcode. Ask your parents.
If you're talking about specific websites that are blocked when you try to access them using Safari (but you can access other sites without a problem), then the blocking is implemented by the administrator of the router and not on your iPod. You'd get the same result if you tried to use a computer on that same network.
Either way, you're out of luck. Sorry.