nmap testing
 

How can I test nmap in real life without breaking the law or pissing off people?
What networks can I test?

You can test YOUR networks and machines that you own. If you get permission from a network owner/administrator, you can then test on their systems too.

What you're asking is similar to saying "How can I test my lock-picking abilities, without breaking the law or pissing people off?"...you do it on your own locks/property, or where you have permission to do so. The same things apply here.

Okay, thank you, TBOne.

You can try this host: http://scanme.nmap.org/
It's referenced in their documentation http://nmap.org/book/man.html